TYPO3 Core

By the way: The whole FE is not reachable anylonger, if this error appears.

solved this problem by adding require_once("class.t3lib_userauthgroup.php"); to class.t3lib_beuserauth.php and now it works again.

Is it possible, that the file is somehow not loaded in some situations?

which extensions do you have loaded?

Just write
require_once (PATH_t3lib.'class.t3lib_beuserauth.php');

just beneath the head of the file t3lib/class.t3lib_tsfebeuserauth.php.

This is in fact missing here. But this could have been intended for security reasons?

i had that bug too, but i have to add
require_once (PATH_t3lib.'class.t3lib_beuserauth.php');
to class.t3lib_tsfebeuserauth.php
AND
require_once (PATH_t3lib.'class.t3lib_userauthgroup.php');
to class.t3lib_beuserauth.php

i got this error too:
http://bugs.typo3.org/view.php?id=4101 [^]
http://bugs.typo3.org/view.php?id=4160 [^]

problem does no longer occur with T3 4.1.5.
Please close

Closing issue as requested by initial reporter.