Updated TYPO3 to version 4.5.0 and got the problem with the module mm_forum.
Click left menu on mm_forum (General settings) > Install > General > Click button Save settings
Fatal error: Call to a member function writelog() on a non-object in /home/data/www/typo3_src/t3lib/class.t3lib_tcemain.php on line 6774
same ... Click left menu on mm_forum > Install > User (User settings) > Click button Save settings
before you upgrade TYPO3 errors mm_forum was not.
Help me fix it

For fast help go to the file 'class.t3lib_tcemain.php' on line 6774 and change with
//$this->BE_USER->writelog(3, 1, 0, 0, 'User %s has cleared the cache (cacheCmd=%s)', array($this->BE_USER->user['username'], $cacheCmd));
Thank you.
Problem solved replacing the two files taken from the Subversion repository extension.
Oops, an error occured!
A cache with identifier "cache_hash" does not exist
How to solve this problem on frontends pages?
HollyHollmann schrieb
For fast help go to the file 'class.t3lib_tcemain.php' on line 6774 and change with
//$this->BE_USER->writelog(3, 1, 0, 0, 'User %s has cleared the cache (cacheCmd=%s)', array($this->BE_USER->user['username'], $cacheCmd));
Works for me with ve_guestbook (same error when submitting FE form for new entry).
Can anyone tell me what this line is about? Writing a log (where?) about user clearing cache??
Can we do without it?
Hello!
Thank you.
I found another solution...
[useCachingFramework] = 1 in "Install Tool"