After upgrade 1.8.0 to 1.8.1 we've encountered a problem entering the site not having logged out after last session.
The next error message is displayed: There is still a valid login for your browser.
Please use this link >>> Logout <<< at first if you would like to renew your session.
When click on LOGOUT 404 web error is displayed:
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
It worked fine before upgrade. How can it be repaired now (except of downgrading back)?
Try clearing your cookies and restart the Apache and SQL server we have several times encountered this problem if we login with same user on multiple browsers.
This has worked with us.