You may get this error when trying to connect to a Terminal Server from Windows 10 or Windows 7.
The workaround is to add the following Registry key on the affected client PC.
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters]
“AllowEncryptionOracle”=dword:00000002
This is NOT a fix. Doing this will bypass the fix for the security vulnerability. But it will get your users going while Microsoft readies a fix.
References:
- https://blogs.technet.microsoft.com/yongrhee/2018/05/09/after-may-2018-security-update-rdp-an-authentication-error-occurred-this-could-be-due-to-credssp-encryption-oracle-remediation/
- https://support.microsoft.com/en-au/help/4093492/credssp-updates-for-cve-2018-0886-march-13-2018
- https://blogs.technet.microsoft.com/askpfeplat/2018/05/07/credssp-rdp-and-raven/