During an upgrade on OTRS 5 and Znuny 6 and above you may get the following error.
sudo -u otrs scripts/DBUpdate-to-6.pl Migration started ... Checking requirements ... Requirement check for: Check framework version ... Requirement check for: Check required Perl version ... Requirement check for: Check required database version ... Requirement check for: Check database charset ... Error: The setting character_set_database is set to 'utf8mb4'. Error: This character set is not yet supported, please see https://bugs.otrs.org/show_bug.cgi?id=12361. Error: Please convert your database to the character set 'utf8'.
Alternatively you may have something like this or similar:
Error: The setting character_set_database is set to 'latin1'.
To change the collation you shall execute a ALTER command on your otrs database. In this example the database is named otrs.
mysql -u root -p ALTER DATABASE otrs CHARACTER SET utf8 COLLATE utf8_general_ci;
your database shall now be on utf8 configured. To check if this is the case you can shall execute
SELECT default_character_set_name FROM information_schema.SCHEMATA WHERE schema_name = "otrs";