Error after TYPO3 update from 4.2 to 4.5:
> Oops, an error occured!
> The requested page didn't have a proper connection to the tree-root!
>
(Broken rootline (failed on page with uid 260))
Solution: TYPO3 backend -> install tool -> update database
From http://lists.typo3.org/pipermail/typo3-english/2011-March/074587.html