Failing upgrade to database schema from 9.0 to 9.1 for a Software Gateway Installation:-
Table 'ssg.databasechangelog' doesn't exist
/etc/my.cnf is the MySQL configuration, it contained a line 'lower_case_table_names=1' meaning that table names are case sensitive. However database contains both databasechangelog and DATABASECHANGELOG which was causing upgrade to fail.
Remove both databasechangelog tables from ssg and upgrade can be performed.