[TYPO3-dev] No pagetree after update to 4.5

[Nico de Haen]

I have a webserver with 3 TYPO3 installations, development, staging and
live all using the same sources. 2 of them showed the new page tree
after the update, the third does not.

They have all the same database content and extensions installed and I
deleted the content of typo3temp/compressor completely. No error
messages, nor in the client (firebug) or on the server (syslog). I can
see that the answer to the 3rd. ajax call

https://mydomain/typo3/ajax.php?ajaxID=ExtDirect::route&namespace=TYPO3.Components.PageTree

is different to that on the working instance, but the pagetree isn't
displayed at all...

Unfortunately it's just the live instance that has the problem. The old
page tree is still working (as I see in a backend module). I also see,
that the spinning loading gif is missing, instead an empty rectangle is
displayed.

Does anyone have an idea what the reason could be and how I can debug?

Thanks for help,

Nico