This vague vBulletin error tends to be caused by vBSEO.
The culprit is the URL character replacement
on usernames with those characters.
For example, if
is set as a replacement URL in the vBSEO admin, then _ is blanked out.
Consider topics on mod_security.
As an example, a topic called "Help with mod_security" (which is a terrible title), the URL would be
Notice the _ is removed.
But if the person posting this question was nifty_username
, then this would break vBulletin. If you clicked that members name, to visit his profile, you'd get:
This user has not registered and therefore does not have a profile to view.
as the URL is
The URL is supposed to be
There does not appear to be any way to fix this. So be very sure NOT to replace characters that are allowed in the username.
This means, of course, that you need to restrict characters allowed in usernames. Refer to this post: http://www.digitalfaq.com/forum/web-...pid-ascii.html
. What we do is monitor new users for illegal names. If one is registered, we inform the user that their name has been to comply with the forum rules, and block that character. (Honestly, it's rarely an issue.)
Hopefully this has helped someone.