Symptoms
When you create an application pool, Horizon automatically displays the applications that are available to all users rather than individual users from the Start menu on all the RDS hosts in the farm or desktop pool. You can select one or more applications from the list. Sometimes the error message "Desktop applications discovery failed" appears when they try to add hosted app pool if there are many UWP apps in that pool.
Cause
There is an overhead with UWP apps to load the UWP manifest file as part of the discovery process.The CreateManifestReader() function will cost over 0.5 second for each UWP application .The cumulative overhead of multiple UWP apps may result in the above error.
Resolution
Currently, there is no resolution.
Workaround
There is no workaround before Horizon version 8.3 .Starting from 8.3, you can wait 3-4 minutes and retry.
