This is usually due to an update corrupting or altering their MSLicensing license key on their local PC. This can also show up for other Windows operating systems, but I’ve never seen it happen until recently with these Windows 10 users.
There are only two solutions:
1. Delete the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSLicensing by opening up regedit as administrator, navigating to the key, and deleting the MSLicensing key. This will delete all subkeys. Then the user has to run Remote Desktop Connection using “Run as Administrator” and it will pull a new license when they connect to us. Since users typically launch RDP through the web browser they may have to:
a. Save the RDP file instead of opening it
b. Find Remote Desktop Connection in their Start menu, right-click on it and select Run As Administrator
c. Once RDP opens up click on Show Options, Open… and then find the RDP file in their downloads.
2. Move to Citrix which doesn’t use Remote Desktop. Obviously this won’t fix RDP for them so they may still have problems connecting to other machines via RDP.