How to Fix RDP “An Internal Error Has Occurred”

Remote Desktop Protocol (RDP) is an essential tool for administrators, developers, and IT professionals who need to access systems remotely. However, encountering the dreaded message “An internal error has occurred” when attempting to connect can be both frustrating and confusing. This generic error doesn’t offer much explanation, leaving you to play tech detective. Fortunately, we’ve compiled a comprehensive guide to help you diagnose and resolve this error step-by-step.

TL;DR

If you’re seeing the “An internal error has occurred” message while using RDP, it could be due to network instability, faulty Remote Desktop settings, or inconsistent user profile states. Start by restarting the RDP service, adjusting Group Policy settings, and disabling persistent bitmap caching. This error is often correctable with a few tweaks you can perform yourself without needing third-party tools.

1. Understanding the “An Internal Error Has Occurred” Message

This RDP error typically appears just before the authentication process or right after entering your credentials. Unlike more descriptive error messages (“The remote session was disconnected,” for example), this one doesn’t provide immediate clues on what went wrong.

The causes may include:

• Misconfigured Remote Desktop settings
• Group Policy inconsistencies
• Network issues like VPN interruptions or DNS conflicts
• Corrupted RDP cache files
• Problems with system services related to Remote Desktop

2. Basic Troubleshooting Steps

Before diving into deep technical configurations, perform these preliminary checks:

• Restart your computer and the remote system – Yes, it’s old advice, but often effective.
• Verify network connection – Ensure that both machines are properly connected to the internet and can ping each other.
• Turn off VPN or proxy – VPNs can sometimes interfere with RDP handshakes or cause timeouts.
• Try a different user account – Determine if the issue is profile-related.

3. Disable and Re-enable Remote Desktop

Sometimes, a quick disable/re-enable of the feature can reset configurations internally. Follow these steps:

1. On the remote computer, go to System Properties.
2. Under the Remote tab, uncheck Allow remote connections to this computer.
3. Click Apply → OK.
4. Reboot your computer.
5. Enable the option again.

This refreshes Remote Desktop Services and may resolve subtle configuration issues.

4. Modify Group Policy Settings

Local Group Policy can sometimes conflict with current session settings. To modify the relevant Group Policy:

1. Press Win + R, type gpedit.msc, and hit Enter.
2. Navigate to Computer Configuration → Administrative Templates → Windows Components → Remote Desktop Services → Remote Desktop Session Host → Security.
3. Double-click Require user authentication for remote connections by using Network Level Authentication.
4. Set it to Disabled.
5. Apply the settings and reboot.

This setting forces RDP connections through an extra layer of authentication which may not be compatible with your setup or older clients.

5. Tweak Remote Desktop Connection Settings

Within the RDP client itself, certain cached settings may result in conflicts. Here’s what to try:

• Open the Remote Desktop Connection client (type mstsc into the Run box).
• Click on Show Options.
• Navigate to the Experience tab and uncheck the Persistent bitmap caching option.

Bitmap caching stores frequently used images locally to improve speed, but when corrupted, it can lead to hidden problems like our current one.

6. Reset the RDP Service

The Remote Desktop service may not be running properly. Resetting it through the Services console can often clear hiccups:

1. Press Win + R, type services.msc, and press Enter.
2. Scroll down to Remote Desktop Services.
3. Right-click it and choose Restart.

Additionally, do the same with Remote Desktop Configuration and Remote Desktop Services UserMode Port Redirector if available.

7. Clear RDP Cache Files

Corrupt RDP cache files can result in persistent errors. You can delete them manually:

1. Navigate to: C:\Users\YourUsername\AppData\Local\Microsoft\Terminal Server Client\Cache.
2. Select all files and delete them.

Make sure RDP is closed while doing this. Deleting these files forces the client to create fresh cache files the next time you connect.

8. Change MTU Settings

MTU (Maximum Transmission Unit) size effects are rare but known to cause RDP issues depending on your network setup. Tweak it using Command Prompt:

First, check the current MTU size:

netsh interface ipv4 show subinterfaces

Then update it (for example, to 1470):

netsh interface ipv4 set subinterface "Wi-Fi" mtu=1470 store=persistent

Replace “Wi-Fi” with your actual interface name. Experiment with values like 1460 or 1452 if the problem persists.

9. Check Windows Firewall or Third-party Security Software

Often overlooked, a security suite or firewall misconfiguration could be blocking RDP connection initiation. Temporarily disable your software firewall or VPN client and attempt to connect again.

To allow RDP through Windows Firewall:

1. Go to Control Panel → System and Security → Windows Defender Firewall.
2. Click on Allow an app or feature through Windows Firewall.
3. Ensure Remote Desktop is checked for both Private and Public networks.

10. Inspect Event Viewer Logs

If none of the above solutions work, it’s time to dig deeper using Event Viewer:

1. Open Event Viewer by typing eventvwr.msc in the Run dialog.
2. Navigate to Windows Logs → Application or System.
3. Look for entries marked as Error or Warning around the same time your RDP error occurred.

Pay attention to logs mentioning RDP, TerminalServices, user-profile, or TLS/SSL issues.

11. Update Windows and Remote Desktop Client

Ensure both the client and the target machine are up to date. Microsoft frequently releases security patches and bug fixes that affect RDP.

• Type winver in the Run box to verify the current Windows version.
• Go to Settings → Update & Security → Windows Update and install pending updates.

Also check for updates to the Remote Desktop app if you’re using the Microsoft Store version.

Conclusion

The “An internal error has occurred” RDP message isn’t as vague as it seems once you break down the common system-level and network causes. By following the solutions outlined above, you’ll likely pinpoint the issue and regain stable access to your remote systems.

If you’d like to minimize future occurrences, consider setting up detailed logging and using modern Remote Desktop applications that offer more diagnostic feedback. Happy troubleshooting!