This is what appears:
[c99ad0719e66fffd1396db68] Caught exception of type Wikimedia\Rdbms\DBQueryError
This is what appears:
[c99ad0719e66fffd1396db68] Caught exception of type Wikimedia\Rdbms\DBQueryError
Please see How to debug for obtaining the full error message, what you provided really isn't enough to go on.