MaxScale caches a lot of information in SQLite databases. These databases can cause issues sometimes. For example, if the schema of the database is not in sync with the current MaxScale version due to a downgrade, then you will see issues. When that happens, MaxScale will not fix itself and the locations of some of these databases can be difficult to track down.
If log_info is set, and if MaxScale opens an SQLite database, it would be extremely helpful if it could write the path of that database to the log file.
As an example, I downgraded from MaxScale 2.3 to 2.2 and have been trying to fix this error for what seems like ages:
And the error was still present after deleting almost every single file in /var/lib/maxscale and /var/cache/maxscale. Apparently this database was in /var/log/maxscale, which is a bit counterintuitive.