1. You install the App-v 4.x server and set the packageroot (content directory) to an alternate location (not the default).
2. You delete the included Default Application, package and content from the disk.
3. You upgrade the server to a newer version of App-V.
After completing the steps above, when clients attempt to stream a virtualized application they receive one of the following errors:
A network error occurred error : XXXXXXXX-XXXXXXXX-20000194
The package requested could not be found in the system data store or the files associated with this package could not be found on the server. Report the following error code to your System Administrator.
Error code: xxxxxxx-xxxxxx0A-20000194
1. Start RegEdit
2. Navigate to the following key:
32-bit Management Server: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SoftGrid\4.5\Server
64-bit Management Server: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\SoftGrid\4.5\Server
3. Set the SOFTGRID_CONTENT_DIR value to the proper content directory location.
4. Restart the server.
This is also discussed on our support team blog at http://blogs.technet.com/b/appv/archive/2010/03/02/after-upgrading-a-microsoft-app-v-server-client-machines-may-receive-00000194-errors-when-trying-to-launch-applications.aspx.