Hello all,
this is just a hint in case anyone has the same problem with the UWL.
It happened to me in 2 cases, that in a Portal 7 SPS9 the UWL only showed a blank page after upgrade from NW04. In NW04 the UWL worked.
The reason for it was something like a corrupt deployment (but there were no according error messages in any log files). The SAP Support told me to redeploy the UWLJWF*.sca according to note 895523, that worked.
You can check whether the deployment is the reason of a non-working UWL setting the property "Launch Web Dynpro UI" to 'no'. Then the old HTMLB sources (that should work) are used (But it is not recommended to use the old sources anymore)
Kind regards
Andreas