Troubleshooting

Common Problems

Encrypted connection issues

If you get the following websockify error when using firefox ...

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

... it means that the certificate used by the websockify for the encrypted connection is not properly signed for the domain it is running on (and firefox only shows the certificate error dialog for normal HTTPS URLs not for WebSocket connections).

If you are using a self-signed certificate, you can force firefox to recognize the certificate by browsing directly to the WebSocket port using HTTPS. The warning dialog should be shown. Click "I Understand the Risks", then click "Add Exception...", then select "Permanently store this exception", and finally click "Confirm Security Exception". The certificate should now be permanently accepted by firefox for both HTTPS and WebSocket WSS connections.

Getting Diagnostic Output

You will need console logging support in the browser. Recent Chrome and Opera versions have built in support. Firefox has a nice extension called "firebug" that gives console logging support.

First, load the noVNC page with logging=debug added to the query string. For example vnc.html?logging=debug.

Then, activate the console logger in your browser. With Chrome it can be activate using Ctrl+Shift+J and then switching to the "Console" tab. With firefox+firebug, it can be activated using Ctrl+F12.

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.

If you suspect a problem with the web-socket-js flash emulator you can turn on debugging by setting window.WEB_SOCKET_DEBUG=1; in include/websock.js. This will enable Flash debug output to the web debug console.

Reporting Issues

If you file a issue/bug, it is very helpful for me to have the last page of console output leading up the problem in the issue report. Other helpful issue/bug information: browser version, OS version, noVNC git version, and VNC server name/version.