One work around is to convert all tables in the database into MyISAM type from InnoDB - FA 2.4.x should still work fine.
The current stock FA v2.4.x does not use any of the InnoDB features like references and cascades yet.

SELECT CONCAT('ALTER TABLE ', TABLE_SCHEMA, '.', TABLE_NAME,' ENGINE=MyISAM;') 
FROM Information_schema.TABLES WHERE TABLE_SCHEMA = 'DBNAME' AND ENGINE = 'InnoDB' AND TABLE_TYPE = 'BASE TABLE';

Replace your FA database name in 'DBNAME' above and then execute the output sql statements.

Alternatively enable InnoDB engine in your my.cnf or my.ini file and restart the MySQL server:

default-storage-engine=innodb
default-table-type=innodb

We been working on the system for about 5 year now.

Suddenly the following error popped up:

DATABASE ERROR : could not get all fiscal years
error code : 1286
error message : Unknown storage engine 'InnoDB'
sql that failed was : SELECT * FROM 4_fiscal_year ORDER BY begin

Please advise what this means and how it can be resolved.