Hello,
This usually happens when the database still contains a reference to a log record that no longer exists. Even if you’re not using the Account_Log association directly, it’s a system association used internally by Mendix.
Safest and quickest fix (for local/dev):
This will recreate the database and remove the broken association.
If this is production, don’t delete the database — instead clean the orphaned records via SQL or restore a backup.
Thanks