5 Ways to Fix Authentication Error Has Occurred | The Function Requested Is Not Supported

'' The function requested is not supported '' is an authentication error which occurs when the computer cannot establish a remote desktop connection. 

Whenever a client requests connection from the RDP server, Credential Security Support Provider (CredSSP) authenticates clients. In cases where the CredSSP fails to authenticate, it can lead to security vulnerabilities. Thus, triggering this error for the applications depending on CredSSP. 

Several users have reported to experience this error after updating windows 10 to the latest version. So users have to be cautious, when there is a new windows update package. If you are also wondering on how to resolve this issue, there are variety of troubleshooting steps.

In this article, I will be demonstrating about the 5 Ways to Fix Authentication Error Has Occurred | The Function Requested Is Not Supported. These instructions allows you to fix this error instantly

Let's get started,

1. Modify Remote Desktop Settings

The first step in resolving the function requested is not supported error is by modifying remote desktop settings. Windows computer allows you to change remote desktop settings from the system properties.

To modify remote desktop settings,

1. Press '' Windows + R ''
2. Type '' sysdm.cpl '' and Press Ok
3. Navigate to the remote tab
4. Uncheck the box '' Allow connections only from computers running remote desktop with network level authentication ''
5. Press Apply and Ok

2. Update Windows

If you are sure that updates don't cause this issue, you can try updating windows to the latest security patches. Windows version which came after 2018, forces every single machine to use CredSSP patch. If this patches are not installed, it means your system has security vulnerabilities. As a result, you will be getting this error the function requested is not supported. By updating windows, you are installing latest CredSSP patches.

3. Uninstall Updates

If the method of updating windows doesn't work, you should also try other way around of uninstalling updates. Now this process differs according to the windows version. Windows 7 computers needs to uninstall KB4103718 updates and Windows 10 computers must uninstall KB4103727 updates. Once the updates are uninstalled restart the computer.

4. Use Group Policy Editor

According to users, changing Encryption Oracle Remediation Policy has effectively fixed the function requested is not supported error. The Encryption Oracle Remediation Policy can be modified using the group policy editor.

To use group policy editor,

1. Press '' Windows + R ''
2. Type '' gpedit.msc '' and Press Ok
3. Go to Computer configuration → Administrative templates → System → Credential delegation
4. Select Encryption Oracle Remediation
5. Check '' Enabled ''
6. Change to '' vulnerable '' in the protection level menu
7. Save and Exit Local Group Policy Editor 

5. Use Registry Editor

Similarly, using registry editor is another approach in fixing the function requested is not supported error. The registry editor can be used to modify the AllowEncryptionOracle parameter. However you must only attempt this method after making a backup or creating a system restore point since this process involves registry keys.

To use registry editor,

1. Press '' Windows + R ''
2. Type '' regedit '' and Press Ok
3. Go to HKEY_LOCAL_MACHINE → Software → Microsoft → Windows → Current Version → Policies → System → CredSSP → Parameters
4. Select AllowEncryptionOracle
5. Type 2 as the value data
6. Press Ok