<?xml version="1.0" encoding="us-ascii"?>
<!-- DFS ActiveDisclosure(SM) XBRL Schema Document - http://www.dfsco.com/financial-services/ -->
<!-- Creation Date      : 2018-08-08T12:40:22.2167764+00:00 -->
<!-- Version            : 2.12.6766.32775 -->
<!-- Package ID         : 1a98dadd00dd4ab8853217d0fd65e9ad -->
<!-- Copyright (c) 2018 Donnelley Financial, LLC. All Rights Reserved. -->
<schema xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric" xmlns:num="http://www.xbrl.org/dtr/type/numeric" xmlns:us-types="http://fasb.org/us-types/2018-01-31" xmlns:stpr="http://xbrl.sec.gov/stpr/2018-01-31" xmlns:srt-types="http://fasb.org/srt-types/2018-01-31" xmlns:naics="http://xbrl.sec.gov/naics/2017-01-31" xmlns:invest="http://xbrl.sec.gov/invest/2013-01-31" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:srt="http://fasb.org/srt/2018-01-31" xmlns:us-gaap="http://fasb.org/us-gaap/2018-01-31" xmlns:dei="http://xbrl.sec.gov/dei/2018-01-31" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:country="http://xbrl.sec.gov/country/2017-01-31" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:currency="http://xbrl.sec.gov/currency/2017-01-31" xmlns:exch="http://xbrl.sec.gov/exch/2018-01-31" xmlns:sic="http://xbrl.sec.gov/sic/2011-01-31" xmlns:fisi="http://www.fiiwarsaw.com/20180630" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.fiiwarsaw.com/20180630" xmlns="http://www.w3.org/2001/XMLSchema">
  <import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance" />
  <import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase" />
  <import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt" />
  <import schemaLocation="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd" namespace="http://xbrl.sec.gov/dei/2018-01-31" />
  <import schemaLocation="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd" namespace="http://fasb.org/us-gaap/2018-01-31" />
  <import schemaLocation="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd" namespace="http://fasb.org/srt/2018-01-31" />
  <import schemaLocation="http://xbrl.fasb.org/us-gaap/2018/elts/us-types-2018-01-31.xsd" namespace="http://fasb.org/us-types/2018-01-31" />
  <import schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/numeric" />
  <import schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/non-numeric" />
  <import schemaLocation="http://xbrl.fasb.org/srt/2018/elts/srt-types-2018-01-31.xsd" namespace="http://fasb.org/srt-types/2018-01-31" />
  <import schemaLocation="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd" namespace="http://xbrl.sec.gov/country/2017-01-31" />
  <import schemaLocation="https://xbrl.sec.gov/currency/2017/currency-2017-01-31.xsd" namespace="http://xbrl.sec.gov/currency/2017-01-31" />
  <import schemaLocation="https://xbrl.sec.gov/exch/2018/exch-2018-01-31.xsd" namespace="http://xbrl.sec.gov/exch/2018-01-31" />
  <import schemaLocation="https://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd" namespace="http://xbrl.sec.gov/invest/2013-01-31" />
  <import schemaLocation="https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd" namespace="http://xbrl.sec.gov/naics/2017-01-31" />
  <import schemaLocation="https://xbrl.sec.gov/sic/2011/sic-2011-01-31.xsd" namespace="http://xbrl.sec.gov/sic/2011-01-31" />
  <import schemaLocation="https://xbrl.sec.gov/stpr/2018/stpr-2018-01-31.xsd" namespace="http://xbrl.sec.gov/stpr/2018-01-31" />
  <annotation>
    <appinfo>
      <link:roleType id="TemplateLink" roleURI="http://www.fiiwarsaw.com/20180630/role/TemplateLink" xmlns:link="http://www.xbrl.org/2003/linkbase">
        <link:definition>00000 - Document - Template Link</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="fisi-20180630_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:title="Calculation Links, all" xlink:type="simple" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="fisi-20180630_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:title="Definition Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="fisi-20180630_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Label Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="fisi-20180630_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation Links, all" xlink:type="simple" />
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document And Entity Information</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfFinancialCondition" id="Role_StatementConsolidatedStatementsOfFinancialCondition">
        <link:definition>100010 - Statement - Consolidated Statements Of Financial Condition</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfFinancialConditionParenthetical" id="Role_StatementConsolidatedStatementsOfFinancialConditionParenthetical">
        <link:definition>100020 - Statement - Consolidated Statements Of Financial Condition (Parenthetical)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfIncome" id="Role_StatementConsolidatedStatementsOfIncome">
        <link:definition>100030 - Statement - Consolidated Statements Of Income</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncome" id="Role_StatementConsolidatedStatementsOfComprehensiveIncome">
        <link:definition>100040 - Statement - Consolidated Statements Of Comprehensive Income</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfChangesInShareholdersEquity" id="Role_StatementConsolidatedStatementsOfChangesInShareholdersEquity">
        <link:definition>100050 - Statement - Consolidated Statements Of Changes In Shareholders&apos; Equity</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfChangesInShareholdersEquityParenthetical" id="Role_StatementConsolidatedStatementsOfChangesInShareholdersEquityParenthetical">
        <link:definition>100060 - Statement - Consolidated Statements Of Changes In Shareholders&apos; Equity (Parenthetical)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/StatementConsolidatedStatementsOfCashFlowsUnaudited" id="Role_StatementConsolidatedStatementsOfCashFlowsUnaudited">
        <link:definition>100070 - Statement - Consolidated Statements Of Cash Flows (Unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPolicies" id="Role_DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPolicies">
        <link:definition>100080 - Disclosure - Basis of Presentation And Summary Of Significant Accounting Policies</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureBusinessCombinations" id="Role_DisclosureBusinessCombinations">
        <link:definition>100090 - Disclosure - Business Combinations</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEarningsPerCommonShareEPS" id="Role_DisclosureEarningsPerCommonShareEPS">
        <link:definition>100100 - Disclosure - Earnings Per Common Share ("EPS")</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecurities" id="Role_DisclosureInvestmentSecurities">
        <link:definition>100110 - Disclosure - Investment Securities</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoans" id="Role_DisclosureLoans">
        <link:definition>100120 - Disclosure - Loans</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssets" id="Role_DisclosureGoodwillAndOtherIntangibleAssets">
        <link:definition>100130 - Disclosure - Goodwill And Other Intangible Assets</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureDerivativeInstrumentsAndHedgingActivities" id="Role_DisclosureDerivativeInstrumentsAndHedgingActivities">
        <link:definition>100140 - Disclosure - Derivative Instruments and Hedging Activities</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareholdersEquity" id="Role_DisclosureShareholdersEquity">
        <link:definition>100150 - Disclosure - Shareholders&apos; Equity</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeLoss" id="Role_DisclosureAccumulatedOtherComprehensiveIncomeLoss">
        <link:definition>100160 - Disclosure - Accumulated Other Comprehensive Income (Loss)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlans" id="Role_DisclosureShareBasedCompensationPlans">
        <link:definition>100170 - Disclosure - Share-Based Compensation Plans</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEmployeeBenefitPlans" id="Role_DisclosureEmployeeBenefitPlans">
        <link:definition>100180 - Disclosure - Employee Benefit Plans</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureCommitmentsAndContingencies" id="Role_DisclosureCommitmentsAndContingencies">
        <link:definition>100190 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureFairValueMeasurements" id="Role_DisclosureFairValueMeasurements">
        <link:definition>100200 - Disclosure - Fair Value Measurements</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureSegmentReporting" id="Role_DisclosureSegmentReporting">
        <link:definition>100210 - Disclosure - Segment Reporting</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies" id="Role_DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>100220 - Disclosure - Basis Of Presentation And Summary Of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEarningsPerCommonShareEPSTables" id="Role_DisclosureEarningsPerCommonShareEPSTables">
        <link:definition>100230 - Disclosure - Earnings Per Common Share ("EPS") (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesTables" id="Role_DisclosureInvestmentSecuritiesTables">
        <link:definition>100240 - Disclosure - Investment Securities (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansTables" id="Role_DisclosureLoansTables">
        <link:definition>100250 - Disclosure - Loans (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsTables" id="Role_DisclosureGoodwillAndOtherIntangibleAssetsTables">
        <link:definition>100260 - Disclosure - Goodwill And Other Intangible Assets (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureDerivativeInstrumentsAndHedgingActivitiesTables" id="Role_DisclosureDerivativeInstrumentsAndHedgingActivitiesTables">
        <link:definition>100270 - Disclosure - Derivative Instruments and Hedging Activities (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareholdersEquityTables" id="Role_DisclosureShareholdersEquityTables">
        <link:definition>100280 - Disclosure - Shareholders&apos; Equity (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeLossTables" id="Role_DisclosureAccumulatedOtherComprehensiveIncomeLossTables">
        <link:definition>100290 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlansTables" id="Role_DisclosureShareBasedCompensationPlansTables">
        <link:definition>100300 - Disclosure - Share-Based Compensation Plans (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEmployeeBenefitPlansTables" id="Role_DisclosureEmployeeBenefitPlansTables">
        <link:definition>100310 - Disclosure - Employee Benefit Plans (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureCommitmentsAndContingenciesTables" id="Role_DisclosureCommitmentsAndContingenciesTables">
        <link:definition>100320 - Disclosure - Commitments and Contingencies (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsTables" id="Role_DisclosureFairValueMeasurementsTables">
        <link:definition>100330 - Disclosure - Fair Value Measurements (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureSegmentReportingTables" id="Role_DisclosureSegmentReportingTables">
        <link:definition>100340 - Disclosure - Segment Reporting (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetails" id="Role_DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetails">
        <link:definition>100350 - Disclosure - Basis of Presentation And Summary Of Significant Accounting Policies (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureBusinessCombinationsNarrativeDetails" id="Role_DisclosureBusinessCombinationsNarrativeDetails">
        <link:definition>100360 - Disclosure - Business Combinations (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEarningsPerCommonShareEPSReconciliationOfEarningsAndSharesUsedInCalculatingBasicAndDilutedEPSDetails" id="Role_DisclosureEarningsPerCommonShareEPSReconciliationOfEarningsAndSharesUsedInCalculatingBasicAndDilutedEPSDetails">
        <link:definition>100370 - Disclosure - Earnings Per Common Share ("EPS") (Reconciliation Of Earnings And Shares Used In Calculating Basic And Diluted EPS) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEarningsPerCommonShareEPSSharesExcludedFromComputationOfDilutedEPSDetails" id="Role_DisclosureEarningsPerCommonShareEPSSharesExcludedFromComputationOfDilutedEPSDetails">
        <link:definition>100380 - Disclosure - Earnings Per Common Share ("EPS") (Shares Excluded from Computation of Diluted EPS) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfInvestmentSecuritiesDetails" id="Role_DisclosureInvestmentSecuritiesAmortizedCostAndFairValueOfInvestmentSecuritiesDetails">
        <link:definition>100390 - Disclosure - Investment Securities (Amortized Cost And Fair Value Of Investment Securities) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesNarrativeDetails" id="Role_DisclosureInvestmentSecuritiesNarrativeDetails">
        <link:definition>100400 - Disclosure - Investment Securities (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesSalesAndCallsOfSecuritiesAvailableForSaleDetails" id="Role_DisclosureInvestmentSecuritiesSalesAndCallsOfSecuritiesAvailableForSaleDetails">
        <link:definition>100410 - Disclosure - Investment Securities (Sales And Calls Of Securities Available For Sale) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesScheduledMaturitiesOfSecuritiesAvailableForSaleAndSecuritiesHeldToMaturityDetails" id="Role_DisclosureInvestmentSecuritiesScheduledMaturitiesOfSecuritiesAvailableForSaleAndSecuritiesHeldToMaturityDetails">
        <link:definition>100420 - Disclosure - Investment Securities (Scheduled Maturities Of Securities Available For Sale And Securities Held To Maturity) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesInvestmentsGrossUnrealizedLossesAndFairValueDetails" id="Role_DisclosureInvestmentSecuritiesInvestmentsGrossUnrealizedLossesAndFairValueDetails">
        <link:definition>100430 - Disclosure - Investment Securities (Investments Gross Unrealized Losses And Fair Value) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansLoanPortfolioDetails" id="Role_DisclosureLoansLoanPortfolioDetails">
        <link:definition>100440 - Disclosure - Loans (Loan Portfolio) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansNarrativeDetails" id="Role_DisclosureLoansNarrativeDetails">
        <link:definition>100450 - Disclosure - Loans (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansRecordedInvestmentByLoanClassInCurrentAndNonaccrualLoansDetails" id="Role_DisclosureLoansRecordedInvestmentByLoanClassInCurrentAndNonaccrualLoansDetails">
        <link:definition>100460 - Disclosure - Loans (Recorded Investment By Loan Class In Current And Nonaccrual Loans) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansSummaryOfImpairedLoansDetails" id="Role_DisclosureLoansSummaryOfImpairedLoansDetails">
        <link:definition>100470 - Disclosure - Loans (Summary Of Impaired Loans) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansCommercialLoanPortfolioCategorizedByInternallyAssignedAssetClassificationDetails" id="Role_DisclosureLoansCommercialLoanPortfolioCategorizedByInternallyAssignedAssetClassificationDetails">
        <link:definition>100480 - Disclosure - Loans (Commercial Loan Portfolio Categorized By Internally Assigned Asset Classification) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansRetailLoanPortfolioCategorizedByPaymentStatusDetails" id="Role_DisclosureLoansRetailLoanPortfolioCategorizedByPaymentStatusDetails">
        <link:definition>100490 - Disclosure - Loans (Retail Loan Portfolio Categorized By Payment Status) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureLoansChangesInTheAllowanceForLoanLossesDetails" id="Role_DisclosureLoansChangesInTheAllowanceForLoanLossesDetails">
        <link:definition>100500 - Disclosure - Loans (Changes In The Allowance For Loan Losses) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsNarrativeDetails" id="Role_DisclosureGoodwillAndOtherIntangibleAssetsNarrativeDetails">
        <link:definition>100510 - Disclosure - Goodwill And Other Intangible Assets (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails" id="Role_DisclosureGoodwillAndOtherIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails">
        <link:definition>100520 - Disclosure - Goodwill And Other Intangible Assets (Changes In Carrying Amount Of Goodwill) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsGrossCarryingAmountAccumulatedAmortizationAndNetBookValueDetails" id="Role_DisclosureGoodwillAndOtherIntangibleAssetsGrossCarryingAmountAccumulatedAmortizationAndNetBookValueDetails">
        <link:definition>100530 - Disclosure - Goodwill And Other Intangible Assets (Gross Carrying Amount Accumulated Amortization and Net Book Value) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureGoodwillAndOtherIntangibleAssetsEstimatedCoreDepositIntangibleAmortizationExpenseDetails" id="Role_DisclosureGoodwillAndOtherIntangibleAssetsEstimatedCoreDepositIntangibleAmortizationExpenseDetails">
        <link:definition>100540 - Disclosure - Goodwill And Other Intangible Assets (Estimated Core Deposit Intangible Amortization Expense) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureDerivativeInstrumentsAndHedgingActivitiesNarrativeDetails" id="Role_DisclosureDerivativeInstrumentsAndHedgingActivitiesNarrativeDetails">
        <link:definition>100550 - Disclosure - Derivative Instruments and Hedging Activities (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureDerivativeInstrumentsAndHedgingActivitiesFairValuesOfDerivativeInstrumentsOnBalanceSheetDetails" id="Role_DisclosureDerivativeInstrumentsAndHedgingActivitiesFairValuesOfDerivativeInstrumentsOnBalanceSheetDetails">
        <link:definition>100560 - Disclosure - Derivative Instruments and Hedging Activities (Fair Values of Derivative Instruments on the Balance Sheet) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureDerivativeInstrumentsAndHedgingActivitiesEffectOfDerivativeInstrumentsOnIncomeStatementDetails" id="Role_DisclosureDerivativeInstrumentsAndHedgingActivitiesEffectOfDerivativeInstrumentsOnIncomeStatementDetails">
        <link:definition>100570 - Disclosure - Derivative Instruments and Hedging Activities (Effect of Derivative Instruments on the Income Statement) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareholdersEquityChangesInSharesOfCommonStockDetails" id="Role_DisclosureShareholdersEquityChangesInSharesOfCommonStockDetails">
        <link:definition>100580 - Disclosure - Shareholders&apos; Equity (Changes In Shares Of Common Stock) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeLossComponentsOfOtherComprehensiveIncomeLossDetails" id="Role_DisclosureAccumulatedOtherComprehensiveIncomeLossComponentsOfOtherComprehensiveIncomeLossDetails">
        <link:definition>100590 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Components Of Other Comprehensive Income (Loss)) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeLossComponentsOfAccumulatedOtherComprehensiveIncomeLossDetails" id="Role_DisclosureAccumulatedOtherComprehensiveIncomeLossComponentsOfAccumulatedOtherComprehensiveIncomeLossDetails">
        <link:definition>100600 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Components Of Accumulated Other Comprehensive Income (Loss)) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureAccumulatedOtherComprehensiveIncomeLossAmountsReclassifiedOutOfEachComponentOfAccumulatedOtherComprehensiveIncomeLossDetails" id="Role_DisclosureAccumulatedOtherComprehensiveIncomeLossAmountsReclassifiedOutOfEachComponentOfAccumulatedOtherComprehensiveIncomeLossDetails">
        <link:definition>100610 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified Out Of Each Component Of Accumulated Other Comprehensive Income (Loss)) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlansSummaryOfRestrictedStockUnitsAndPerformanceShareUnitsActivityDetails" id="Role_DisclosureShareBasedCompensationPlansSummaryOfRestrictedStockUnitsAndPerformanceShareUnitsActivityDetails">
        <link:definition>100620 - Disclosure - Share-Based Compensation Plans (Summary Of Restricted Stock Units And Performance Share Units Activity) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlansNarrativeDetails" id="Role_DisclosureShareBasedCompensationPlansNarrativeDetails">
        <link:definition>100630 - Disclosure - Share-Based Compensation Plans (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlansSummaryOfRestrictedStockAwardsActivityDetails" id="Role_DisclosureShareBasedCompensationPlansSummaryOfRestrictedStockAwardsActivityDetails">
        <link:definition>100640 - Disclosure - Share-Based Compensation Plans (Summary Of Restricted Stock Awards Activity) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlansSummaryOfStockOptionActivityDetails" id="Role_DisclosureShareBasedCompensationPlansSummaryOfStockOptionActivityDetails">
        <link:definition>100650 - Disclosure - Share-Based Compensation Plans (Summary Of Stock Option Activity) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureShareBasedCompensationPlansShareBasedCompensationExpenseIncludedInConsolidatedStatementsOfIncomeDetails" id="Role_DisclosureShareBasedCompensationPlansShareBasedCompensationExpenseIncludedInConsolidatedStatementsOfIncomeDetails">
        <link:definition>100660 - Disclosure - Share-Based Compensation Plans (Share-Based Compensation Expense Included In Consolidated Statements Of Income) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEmployeeBenefitPlansComponentsOfNetPeriodicBenefitExpenseDetails" id="Role_DisclosureEmployeeBenefitPlansComponentsOfNetPeriodicBenefitExpenseDetails">
        <link:definition>100670 - Disclosure - Employee Benefit Plans (Components Of Net Periodic Benefit Expense) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureEmployeeBenefitPlansNarrativeDetails" id="Role_DisclosureEmployeeBenefitPlansNarrativeDetails">
        <link:definition>100680 - Disclosure - Employee Benefit Plans (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureCommitmentsAndContingenciesOffBalanceSheetCommitmentsDetails" id="Role_DisclosureCommitmentsAndContingenciesOffBalanceSheetCommitmentsDetails">
        <link:definition>100690 - Disclosure - Commitments And Contingencies (Off-Balance Sheet Commitments) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureCommitmentsAndContingenciesNarrativeDetails" id="Role_DisclosureCommitmentsAndContingenciesNarrativeDetails">
        <link:definition>100700 - Disclosure - Commitments And Contingencies (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsAssetsMeasuredAtFairValueOnARecurringAndNonRecurringBasisDetails" id="Role_DisclosureFairValueMeasurementsAssetsMeasuredAtFairValueOnARecurringAndNonRecurringBasisDetails">
        <link:definition>100710 - Disclosure - Fair Value Measurements (Assets Measured At Fair Value On A Recurring And Non-Recurring Basis) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsNarrativeDetails" id="Role_DisclosureFairValueMeasurementsNarrativeDetails">
        <link:definition>100720 - Disclosure - Fair Value Measurements (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsAdditionalQuantitativeInformationAboutAssetsMeasuredAtFairValueOnARecurringAndNonRecurringBasisDetails" id="Role_DisclosureFairValueMeasurementsAdditionalQuantitativeInformationAboutAssetsMeasuredAtFairValueOnARecurringAndNonRecurringBasisDetails">
        <link:definition>100730 - Disclosure - Fair Value Measurements (Additional Quantitative Information About Assets Measured At Fair Value On A Recurring And Non-Recurring Basis) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsCarryingAmountEstimatedFairValueAndPlacementInFairValueHierarchyOfFinancialInstrumentsDetails" id="Role_DisclosureFairValueMeasurementsCarryingAmountEstimatedFairValueAndPlacementInFairValueHierarchyOfFinancialInstrumentsDetails">
        <link:definition>100740 - Disclosure - Fair Value Measurements (Carrying Amount, Estimated Fair Value, And Placement In Fair Value Hierarchy Of Financial Instruments) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureSegmentReportingNarrativeDetails" id="Role_DisclosureSegmentReportingNarrativeDetails">
        <link:definition>100750 - Disclosure - Segment Reporting (Narrative) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureSegmentReportingBusinessSegmentAssetsDetails" id="Role_DisclosureSegmentReportingBusinessSegmentAssetsDetails">
        <link:definition>100760 - Disclosure - Segment Reporting (Business Segment Assets) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.fiiwarsaw.com/20180630/taxonomy/role/DisclosureSegmentReportingBusinessSegmentProfitLossDetails" id="Role_DisclosureSegmentReportingBusinessSegmentProfitLossDetails">
        <link:definition>100770 - Disclosure - Segment Reporting (Business Segment Profit (Loss)) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </appinfo>
  </annotation>
  <element id="fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" name="InvestmentSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <element id="fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" name="InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <element id="fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss" name="InvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" name="InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_Series3PreferredStockMember" name="Series3PreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_NoninterestIncomeServiceChargesOnDeposits" name="NoninterestIncomeServiceChargesOnDeposits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_AtmAndDebitCard" name="AtmAndDebitCard" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_NoninterestIncomeInvestmentsInLimitedPartnerships" name="NoninterestIncomeInvestmentsInLimitedPartnerships" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_NoninterestIncomeLoanServicing" name="NoninterestIncomeLoanServicing" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_GainLossOnContingentConsiderationLiabilityAdjustment" name="GainLossOnContingentConsiderationLiabilityAdjustment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_DecreaseIncreaseInNetUnsettledSecurityPurchases" name="DecreaseIncreaseInNetUnsettledSecurityPurchases" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_NatureOfBusinessOperationsPolicyTextBlock" name="NatureOfBusinessOperationsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_RetailLoanPortfolioCategorizedByPaymentStatusTableTextBlock" name="RetailLoanPortfolioCategorizedByPaymentStatusTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_ScheduleOfShareBasedCompensationRestrictedStockUnitsAndPerformanceShareUnitsActivityTableTextBlock" name="ScheduleOfShareBasedCompensationRestrictedStockUnitsAndPerformanceShareUnitsActivityTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_NumberOfStatesInWhichEntityProvidesServices" name="NumberOfStatesInWhichEntityProvidesServices" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect" name="TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_HNPCapitalMember" name="HNPCapitalMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_RobshawJulianAssociatesIncMember" name="RobshawJulianAssociatesIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_CourierCapitalMember" name="CourierCapitalMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_IncrementalCommonSharesAttributableToVestingOfRestrictedStockAwards" name="IncrementalCommonSharesAttributableToVestingOfRestrictedStockAwards" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_DebtSecuritiesAvailableForSaleAndHeldToMaturityRestricted" name="DebtSecuritiesAvailableForSaleAndHeldToMaturityRestricted" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <element id="fisi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInInvestments" name="AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInInvestments" name="AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInInvestments" name="AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_InvestmentSecuritiesAccumulatedUnrecognizedHoldingLoss" name="InvestmentSecuritiesAccumulatedUnrecognizedHoldingLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValue" name="InvestmentSecuritiesContinuousUnrealizedLossPositionFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <element id="fisi_AvailableForSaleSecuritiesInUnrealizedLossPositionsTwelveMonthsOrLongerQualitativeDisclosureNumberOfPositions" name="AvailableForSaleSecuritiesInUnrealizedLossPositionsTwelveMonthsOrLongerQualitativeDisclosureNumberOfPositions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <element id="fisi_AvailableForSaleSecuritiesInUnrealizedLossPositionsLessThanTwelveMonthsQualitativeDisclosureNumberOfPositions" name="AvailableForSaleSecuritiesInUnrealizedLossPositionsLessThanTwelveMonthsQualitativeDisclosureNumberOfPositions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <element id="fisi_LoansAndLeasesReceivableDeferredLoanFeesCosts" name="LoansAndLeasesReceivableDeferredLoanFeesCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_CommercialAndIndustrialMember" name="CommercialAndIndustrialMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_ConsumerIndirectMember" name="ConsumerIndirectMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_ConsumerOverdraftsMember" name="ConsumerOverdraftsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_BankingSegmentMember" name="BankingSegmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_NonBankingMember" name="NonBankingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_ShareholdersEquityLineItems" name="ShareholdersEquityLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_ShareholdersEquityTable" name="ShareholdersEquityTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_PerformanceShareUnitsMember" name="PerformanceShareUnitsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_ManagementStockIncentivePlanMember" name="ManagementStockIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_RelativeShareholderReturnPerformanceRequirementMember" name="RelativeShareholderReturnPerformanceRequirementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_DirectorStockIncentivePlanMember" name="DirectorStockIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_VestedImmediatelyMember" name="VestedImmediatelyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_VestedAfterCompletionOfOneYearServiceRequirementMember" name="VestedAfterCompletionOfOneYearServiceRequirementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_NumberOfNonEmployeeDirectors" name="NumberOfNonEmployeeDirectors" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_SalariesAndEmployeeBenefitsMember" name="SalariesAndEmployeeBenefitsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_OtherNoninterestExpensesMember" name="OtherNoninterestExpensesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_ForwardSalesCommitments" name="ForwardSalesCommitments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_LoansHeldForSaleMember" name="LoansHeldForSaleMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_CollateralDependentImpairedFinancingReceivableMember" name="CollateralDependentImpairedFinancingReceivableMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_LoanServicingRightsMember" name="LoanServicingRightsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_OtherRealEstateOwnedOtherReceivableMember" name="OtherRealEstateOwnedOtherReceivableMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <element id="fisi_FairValueMeasurementWithUnobservableInputValuePercentage" name="FairValueMeasurementWithUnobservableInputValuePercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <element id="fisi_NonMaturityDepositsFairValueDisclosure" name="NonMaturityDepositsFairValueDisclosure" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <element id="fisi_HoldingCompanyAndOtherSegmentMember" name="HoldingCompanyAndOtherSegmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</schema>
