Troubleshooting - novnc/noVNC GitHub Wiki

Common Problems

Encrypted connection issues

If you are using a self-signed certificate and are having trouble connecting and or seeing errors from websockify that look like this then see the websockify encryption page for workarounds:

handler exception: [Errno 1] _ssl.c:392: error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca

HTTPS is required for full functionality

This is seen when using noVNC without an encrypted connection. It is not enough to just change the URL to https://, since this will trigger this error message from websockify/novnc_proxy:

SSL connection but '/home/user/noVNC/utils/websockify/self.pem' not found

Follow the steps in the websockify encryption page to enable HTTPS.

Getting Diagnostic Output

Logs for noVNC are written to the browser's Javascript console.

First, load the noVNC page with logging=debug added to the query string, for example vnc.html?logging=debug. Alternatively, change logging in the settings.

Then, open the Javascript console in your browser:

• With Chrome it can be opened using Ctrl+Shift+J and then switching to the "Console" tab.
• With Firefox, it can be opened using F12.
• In iOS (iPhone and iPad) you can activate the Debug Console via the main Settings app under Safari->Developer->Debug Console.

Now reproduce the problem. The console log output will give more information about what is going wrong and where in the code the problem is located.

Reporting Issues

If you file an issue or bug, it is very helpful to have the last page of console output leading up to the problem in the issue report.

For more info on what to include in the bug report, see the questions in the issue report form