Microsoft recently published a Guide on how to Update your Management-Server to App-V 5.1. After the upgrade you may encounter the following error when accessing the Publishing Service:
Publishing metadata not ready
Object reference not set to an instance of an object
The actual update itself is a bit tricky because the setup process resets the current Database Server which is stored in the Registry of the Management Server. After the setup you need to manually revert the Registry-Value to the original state before the update. This is all covered in the linked Blog-Post by Microsoft.
Regarding the Publishing Error, follow the Steps as below:
1. Start by making a backup/snapshot of your management server. Everything feels better with a backup. 🙂
2. Use the following PowerShell Commands to stop the App-V related Application Pools on your Management-Server:
Stop-WebAppPool -Name AppVManagement
Stop-WebAppPool -Name AppVPublishing
3. Navigate to the following Directories and remove the Publishing Metadata XML Files in it:
4. Start the App-V Management Application Pool
Start-WebAppPool -Name AppVManagement
5. Start the App-V Publishing Management Pool
Start-WebAppPool -Name AppVPublishing
You should see that the deleted Publishing Metadata XML Files are getting recreated and your Publishing-Service should be up and running again.