I searched the Gemini bug list, and could not find this one.  There was a previous post about it by another user that never received a response.

It's easy to duplicate and what I would judge as "major" if not a "show stopper".

If a "new thread" is opened by a user, and the user is distracted by a meeting, lunch, whatever, and "submits" the thread after his userID has been logged out, the Forum accepts the post, and the entire group is promptly lost.  Other users (including admin and host) only see the errant post with the critical error notice.  Other posts are not visible, and admin/host cannot delete the post.  The right pane of the post has the "username" replaced with some gibberish, including ineffective "next" and "back" arrows and other data that forces the thread's table into becoming 1.5" or so high.

Short of editing the SQL database, the group must be deleted.

The exact same error, with posted event log is already posted on the forum:

http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/7/threadid/195603/scope/posts/Default.aspx

Duplicating the problem forces me to delete a forum group, since I'm not up to speed on SQL editing, and I'd rather not do it just to duplicate the error again, since there are messages that will be lost.  Just click "new thread" and wait the login timeout period before submitting. Fails every time.

My failure is on DNN core 4.08.03  and Forum module 04.04.03.

Thanks.