How to fix error rpc-s-unknown-authn-level in Windows 11

Solution Steps

1. 1 Press Windows key + R, type 'regedit', and press Enter. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole. Look for 'DefaultAuthenticationLevel'. If it exists, double-click it and set the value to a valid number: 0 (None), 1 (Connect), 2 (Call), 3 (Packet), 4 (Packet Integrity), or 5 (Packet Privacy). If it doesn't exist, create a new DWORD (32-bit) Value with that name and set it to 1. This sets a valid default for all DCOM calls.
2. 2 If the error is specific to a service, check the service's configuration. In Services, right-click the service, select 'Properties', and go to the 'Log On' tab. Ensure the account has the right to log on as a service. Sometimes the authentication level is set in the service's own configuration file.
3. 3 If the application has a configuration file (like .config or .xml), look for authentication level settings and ensure they use valid values. For example, in .NET applications, you might see 'authentication level' in the app.config.
4. 4 Restart the computer to apply changes.