While testing the App-V 5.0 SP2 functionality, I once came across the issue that the “Microsoft App-V Clinet” service couldn’t be started:
I found out that the there’s was an issue with the content of the folder C:\ProgramData\Microsoft\AppV\Client\Catalog\Packages\. I had one package in there, but obviously there was something wrong or misconfigured. After renaming the Catalog folder, the service was able to start. So whenever you face the issue that the service won’t start, try first to rename the folder C:\ProgramData\Microsoft\AppV\ and check if it fixes the issue. If so, you can deep dive into the subfolders/files to figure out which one exactly cause the issue.