So you go to login to via RDP to a server, workstation or remote PC and you get this error:

Not to worry, here is the fix as well as the why.
First run windows update on your local system and try again.
Quick fix: (not secure)
- Use the Windows+R key to open the Run Command. (If you keyboard lacks the windows key you can use Ctrl+Alt+DEL, open task manager, then click file and "Run".)
- In the run command type in gpedit.msc which will open the Local Group Policy Editor.
- Expand Computer Configuration > Administrative Templates > System > Credentials Delegation.
- Update the Encryption Oracle Remediation policy to Enabled, then change Protection level to Vulnerable.
- After doing this it is advisable to update your remote system and switch these settings back.
Proper fix: (secure)
Update the remote server, in some cases the remote server may show that is it up to date in which case you may have a compromised system and will need to follow the following steps in order to force the update after which you should do a full scan on the system for potential malware.
Why:
After the May 2018 update RDP no longer connects by default to a remote system that is not running the CredSSP update.
Open the OSD display by pressing one of the buttons next to the power,
Now, press buttons in order from left to right: #5, #3, #5, #5, #3, #5, #5
You should now have "Refresh Num Rate" selected, we need to turn this off.
Press #3, #5
Now press #2, #5, #5,
We are now selected on "Game Mode", we need to save the settings we just changed so the display does not reset next time it switches modes or is turned off and back on.
Press #3,
Select your save mode then press #3 to save.
The framerate should now be turned off and should not turn back on.
At times RDPclip will become corrupted and require a process restart. Here are the steps needed to do this:
- Open Task Manager on the RDP session
- Ctrl+Alt+End, then choose Start Task Manager
- Under processes tab find rdpclip.exe and end the process
- Click File > New Task (Run..) > rdpclip > OK
- That's it your done and the clipboard should be working again.
Open CMD.exe as admin,
- Use Windows + "X key"
- Choose "Windows Powershell (Admin)"
- Type in: SFC /SCANNOW
- Let this run and fix any file problems
- Now run: DISM /Online /Cleanup-Image /RestoreHealth
- This may stall from time to time as it fixes registry entries.
Once these are both done restart your PC and scan for viruses using your preferred antivirus.
I've run into this issue several times now where windows explorer 10 has some sort of conflict with windows search service. This happens on clean installs and more frequently to those that have upgraded from windows 7 or 8 to windows 10.
Here is the quick fix to resolve this:
Ctrl+Alt+Del > Select "Task Manager"
Once task manager opens select the wind and type "w" until it selects "Windows Explorer", right click and end task. This will cause all of your windows explorer items to be removed from the windows interface and you should notice the pc has returned to normal, no longer slow.
If this is the case continue with the next step,
Choose "file" from "Task Manager" then enter "services.msc" and click "ok", now scroll down to "Windows Search" double click and change the startup type to "Disabled" then "Stop" the service.
(please note, this will disable your windows search function)
To restore windows explorer select "file" from the task manager and "run new task" enter "explorer.exe" and click ok. Everything should now be working properly other than "Windows Search" which is now disabled.