If you encounter this error on an Azure Virtual Machine, the certificate store might be corrupt.
Expired self-signed certificates are a primary cause of error 0x904. Windows generates these for RDP connections, but they do not always renew automatically. i remote desktop connection error code 0x904 install
Check the expiration date. If expired, right-click and Delete the old certificate. If you encounter this error on an Azure
Open Command Prompt as Administrator and run: restart-service termserv -force . especially over VPNs.
Execute: Rename-Item -path "C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys" -NewName "MachineKeys_old" .
Use PowerShell to ensure port 3389 is open: Test-NetConnection [server_name] -Port 3389 . 4. Network and VPN Stability
Error 0x904 is frequently linked to "dodgy" or unstable network paths, especially over VPNs.