[TYPO3-install] Cannot login to BE after upgrade from 4.2 to 4.3.3

[Eduardo Trápani]

>> Any ideas?  I know this question has already been asked, but the 
>> proposed solutions have not fixed the problem for me.
> 
> I would try to disable all extensions first. Go to your 
> typo3conf/localconf.php and modify the extension list to remove 
> extensions (make backup first!)

Great!  I didn't know I could disable them like that.  Disabling all extensions 
and changing $TYPO3_CONF_VARS['BE']['loginSecurityLevel'] from 'normal' to 
'superchallenged' (which hadn't worked before) did the trick.

Now I only have to find the offending extension.

Thanks a lot!

Eduardo.