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    ACCESSION NUMBER:		0000950170-23-055607
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		14
    CONFORMED PERIOD OF REPORT:	20231026
    ITEM INFORMATION:		Results of Operations and Financial Condition
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20231026
    DATE AS OF CHANGE:		20231026

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			FINANCIAL INSTITUTIONS INC
    		CENTRAL INDEX KEY:			0000862831
    		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
    		IRS NUMBER:				160816610
    		STATE OF INCORPORATION:			NY
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-26481
    		FILM NUMBER:		231350253

    	BUSINESS ADDRESS:
    		STREET 1:		220 LIBERTY STREET
    		CITY:			WARSAW
    		STATE:			NY
    		ZIP:			14569
    		BUSINESS PHONE:		5857861100

    	MAIL ADDRESS:
    		STREET 1:		220 LIBERTY STREET
    		CITY:			WARSAW
    		STATE:			NY
    		ZIP:			14569
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    Document 1 - file: fisi-20231026.htm

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    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
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    <TYPE>JSON
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