After moving the SSRS to another server, following the instructions provided on:
Moving SQL Server Reporting Services (SSRS) to a different server. (78487)
You may need to reconfigure QKP to point to the new server.
1) Locate the file Settings.xml in folder OKP installation location. Default:
C:\Program Files (x86)\Quest Software\Knowledge Portal\Configurations
2) Change the settings in the file so that both the ReportingServicesURL and ReportingGUI are pointing to the new SSRS instance;
3) Restart the service and test the access.
If you are still experiencing difficulties, please review the settings listed on following registry key: