FIX: Remote Desktop Connection: An authentication error has occurred. The function requested is not supported

 

Issue: Remote Desktop Connection: An authentication error has occurred. The function requested is not supported... This could be due to CredSSP encryption oracle remediation. 

To Resolve this issue, you have to add some registry on source machine. Source machine means the computer from where you want to RDP to your target server. 

Press Window button + R to open Run.

Write Regedit and press enter.

Go to below path: 

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System

Right click on System and create New  > Keys name it 'CredSSP'

Right click on CredSSP and Create New >  Keys name it 'Parameters'

Right click on Parameters and New > DWORD (32 bit)

Name it AllowEncryptionOracle  and select Decimal and put value 2 and press OK

Remote desktop connection should be fixed. If it doesn't work follow next step:

Press Window button + R to open Run again.

Write gpedit.msc and enter.

Expand Computer Configuration

Expand Administrative Template 

Expand  System 

Select Credentials Delegation 

Double click Encryption Oracle Remediation 

Select Protection Level : Vulnerable and Select Enable 

Finally Press OK

Thank you.