“An Authentication Error Has Occurred. The Function Requested Is Not Supported”

This error happens when customers attempt to set up an unsecure reference to a distant desktop. It occurs if the CredSSP(Credential Security Support Provider) encryption has not been up to date to model ‘CVE-2018-0886’ or if the Remote Desktop Client refuses to attach as a consequence of network stage authentication being enabled.

The best approach to remedy ‘An Authentication Error has Occurred. The Function Requested Is Not Supported’ could be to update the CredSSP protocol. If the CredSSP is up-to-date and also you’re nonetheless encountering this drawback, you possibly can disable sure group insurance policies to repair the difficulty.

Update CredSSP Protocol

The CredSSP protocol is liable for authenticating and establishing a safe reference to the distant desktop. It works by delegating credentials of the consumer to the distant server. Updating the protocol via Windows update can assist repair the difficulty.

To update the CredSSP protocol

1. Press the Windows key + I to open Settings
2. Click on the Windows update tab
3. Click on the Check for updates button
   
4. If updates can be found, choose Download & Install to start the update

If the automated update course of fails to update the protocol, you will have to manually obtain and update the safety patches. First, verify for the model of Windows put in in your device

1. Open Run by urgent the Windows key + R 
2. Type winver on the console and observe down the knowledge displayed 
   
3. After, go to Microsoft’s Security Response Center 
   
4. Search for the most recent safety patch  or one that’s suitable together with your model of Windows
   
5. Download and set up the safety patch to update the protocol

Perform the update on each the shopper and server computer systems to unravel the error.

Change/Update Group Policies

If updating the CredSSP protocol nonetheless shows the error, you will have to make adjustments on the Group policy. To be exact, change the ‘Encryption Oracle Remediation’,  ‘Require user authentication for remote connections by using Network Level Authentication’ and ‘Require use of a specific security layer for remote (RDP) connections’ to susceptible and disabled.

To change the Encryption Oracle Remediation policy

1. Open Run and kind gpedit.msc to open the Group Policy Editor
2. Now, navigate to
   Computer Configuration> Administrative Templates> System> Credentials Delegation
3. Open the folder and inside, open the Encryption Oracle Remediation setting
   
4. Set it to Enabled and alter the safety stage to Vulnerable
   
5. Click on OK and Apply to avoid wasting change

To change the ‘Network Level Authentication’ and ‘Require use of specific security layer for remote (RDP) connections’ insurance policies

1. From Group policy editor, navigate to
   Computer Configuration> Administrative Templates> Windows Components> Remote Desktop Services> Remote Desktop Session Host> Security
   
2. From the folder, open every policy and set them to Disabled
   
3. Now open Windows PowerShell and kind gpupdate /power to use the settings instantly.
   
4. Log out or restart your device to make the adjustments take impact 

Change Protection Level from Registry

If you might be working the house model of Windows, you possibly can nonetheless change the ‘Encryption Oracle Remediation’ setting from the Windows Registry editor.

1. Open Run and kind regedit to open the Registry editor
2. Navigate to ComputersHKLMSoftwareMicrosoftWindowsCurrentVersionPoliciesSystemCredSSPParameters
3. Search for the AllowEncryptionOracle key and open it
4. Set the Value information to 2 and click on on OK

If you can not discover the subkey or the worth, you will have to create an new key

1. On the Registry, navigate to ComputersHKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionPoliciesSystem
2. Click on New> Key and title it CredSSP
   
3. Click on the important thing and once more, create a brand new key inside it named Parameters
   
4. Open the Parameters key and right-click on it to pick out New> DWORD Value(32 bit) 
5. Name the worth as AllowEncryptionOracle
   
6. Open it and set the Value information to 2

Disable Network Level Authentication

By disabling network stage authentication, you possibly can cease the “An authentication error has occurred. The function requested is not supported” error from showing quickly. The authentication technique makes use of the CredSSP for pre-authenticating the distant desktop connection.

Note: This technique nevertheless, is a workaround resolution solely and may go away your device susceptible.

1. Open Settings by urgent the Windows key + I
2. On the System tab, scroll down and click on on About
3. Click on Advanced system settings
   
4. On the brand new window, click on on the Remote tab
5. Uncheck the ‘Allow connections only from computers running Remote Desktop with Network Level Authentication’ possibility
6. Click on OK and Apply to avoid wasting adjustments

From Command Prompt

By using command immediate, you can even change the Encryption Oracle to susceptible. This course of nevertheless, will make your device inclined to safety dangers. 

1. Open Run and kind cmd 
2. Press the Ctrl + Shift + Enter keys to open Command immediate with elevated entry
3. On the console, sort
   reg add "HKLMSoftwareMicrosoftWindowsCurrentVersionPoliciesSystemCredSSPParameters" /f /v AllowEncryptionOracle /t REG_DWORD /d 2
   
4. Close the Command immediate window after which restart your device

Check if the error happens whereas establishing distant connection