Remote Desktop 'An Internal Error Has Occurred' — RDP Connection Failed

Fix Remote Desktop Protocol internal error that prevents connecting to remote computers, caused by RDP service issues, authentication failures, or network problems. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: The 'An internal error has occurred' message is a generic RDP connection failure. Remote Desktop requires the target machine to have Remote Desktop enabled and running. RDP uses port 3389 by default and requires network connectivity between the two machines. Network Level Authentication (NLA) can cause connection failures if credentials are mismatched. The RDP services (TermService, SessionEnv) must be running on the remote machine. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Remote Desktop services not running or crashed on the target machine. RDP security settings (NLA, TLS version) mismatch between client and server. Firewall blocking port 3389 on the remote machine or network. RDP certificate expired or corrupted on the remote machine. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Restart the Remote Desktop client and try connecting again (transient error). On the remote machine: ensure Remote Desktop is enabled in Settings > System > Remote Desktop. Verify RDP services: services.msc > Remote Desktop Services > ensure it is Running. Check firewall: ensure port 3389 is open on the remote machine's firewall. Delete saved RDP credentials: Credential Manager > Windows Credentials > remove the remote host entry, then reconnect. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Windows Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.