Ensure that Remote Desktop (WebSocket) is allowed through the Windows Defender Firewall on both the client and host machines. If using a VPN, ensure it is stable; switching from a computer name to a direct IP address in the connection field can also bypass local DNS resolution issues.
Remote Desktop error code 0x904 (often accompanied by extended error code 0x7) primarily indicates a network connection failure
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\Client Create DWORD: "AllowCertRevocationCheck" = 0
Open the Start menu, type control firewall.cpl , and press . i remote desktop connection error code 0x904 better
Reboot the VM; Windows will recreate a healthy folder and fresh certificates.
– Systems engineer specializing in Windows RDP, certificate services, and remote work infrastructure. If this article helped you, consider sharing it with a colleague who still restarts their router for error 0x904.
Corrupted DNS caches or misrouted IP addresses regularly trigger the 0x904 handshake timeout. Flushing these configurations establishes a clean slate. Ensure that Remote Desktop (WebSocket) is allowed through
If none of the above resolves 0x904 :
Always start with the non-invasive solutions (checking the firewall, testing the network port, and rebooting the server) before proceeding to Group Policy or Registry edits, which you should always back up first. By systematically investigating the causes listed here, you can diagnose and resolve this error and restore seamless remote connectivity.
The most common cause of error 0x904 is a mismatch. Microsoft released patches in 2018 that changed how RDP negotiates encryption. If your client is patched but the server isn’t (or vice versa), you get 0x904. Reboot the VM; Windows will recreate a healthy
Go to Personal > Certificates or Remote Desktop > Certificates .
If you are attempting to connect to your host PC from outside your local home network, your router likely does not know where to send the incoming RDC data packet. Step 1: Assign a Static IP to the Host PC
If encryption mismatches are suspected, you can force the server to use a specific security layer via the Group Policy Object (GPO). Unable to RDP into some Windows Servers - Error code: 0x904
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A corrupted terminal services licensing cache can mimic error 0x904, even if the underlying security is fine. Most users ignore this, but cleaning it provides a better long-term experience.