Answer
Capture the full server-side debug detail via a browser HAR export: enable Debug in the client, open Chrome DevTools (F12), reproduce the error, then export the Network/Server tab activity as a .har file. That file contains the complete request/response data from the server (including the actual underlying error the generic client-side message is hiding) — reviewing it (after scrubbing any confidential data) is the way to get from a generic 'Database error occurred' message to the actual root cause, since the client-side error text alone doesn't include enough detail to diagnose this kind of Command Group failure.