We had errors with the App-V publishing service on one of our AppV 5 infrastructure servers. Hotfix KB2940354 had already been installed. But during the remove of the APp-V 5.0 SP1 client, the hotfixes are not removed, nor can they be uninstalled.
The Application Virtualization setup has failed because a more recent version of the App-V is already installed. To Complete the setup, uninstall the existing version of App-V.
Delete this key:
Simply delete any keys related to any App-V hotfixes prior to reinstalling a lower version of the App-V server.