A few days ago, I temporarily banned two of my users for the first time and here's what they see:
SQL ERROR [ mysqli ]
Incorrect integer value: 'ANONYMOUS' for column 'user_id' at row 1 
Could you guys help me fix this? Thanks
Edit: OK it seems I fixed it, so banned users are supposed to see "the submitted form is invalid", correct?
The culprit was David63's extension 'Log user connections', I will report the bug.