Before diving into deep system settings, verify the most fundamental requirements are met on both the client and the server:
The self-signed certificate the host uses to encrypt the connection might have expired or become corrupted, halting the TLS handshake.
Use the feature in the Azure Portal to execute: Rename-Item -path "C:\ProgramData\Microsoft\Crypto\RSA\MachineKeys" -NewName "MachineKeys_old" .
Navigate to Remote Desktop > Certificates . If the certificate is expired, right-click and Delete it. Before diving into deep system settings, verify the
The server is rejecting the connection because it cannot verify the client’s identity or trust the certificate chain being presented. This is rarely a network outage; it is an encryption and trust failure .
The Event Viewer is your most powerful diagnostic tool. It provides precise details that the generic RDP error message does not.
The RDP service relies on a self-signed certificate for encryption. If this certificate is corrupted, your RDP connections will fail. If the certificate is expired, right-click and Delete it
Misconfigured VPN tunnels dropping the UDP packets used by modern RDP.
On the target machine, open (Win+R) and type gpedit.msc .
This usually appears right before the connection fails, often after entering your credentials. Below is exactly what causes this error and how to fix it. The Event Viewer is your most powerful diagnostic tool
Error 0x904 generally triggers when the Remote Desktop Protocol (RDP) client initiates a connection, but the host server fails to complete the handshake. The "Extended Error 0x7" suffix is often a signal that the underlying issue is related to or access denied errors at the system level. Common triggers include:
Extended error code: 0x7
Under the Remote Desktop section, the box that says "Allow connections only from computers running Remote Desktop with Network Level Authentication (recommended)" . Click Apply and then OK . 2. Configure RDP to Use TCP Only (Disable UDP)
Solving the Remote Desktop Connection error code 0x904 (extended error 0x7) typically requires addressing security certificate permissions or network configurations. This specific combination often points to a failure in establishing a secure TLS tunnel because the Remote Desktop Service cannot access the private key of the assigned certificate. Understanding Error 0x904 (Extended 0x7)