Weird noVNC error

The webconf works fine and I can still access the VNC engines link which works without issue. However, the normal VNC link for the Zythian UI only gives an error now and I can’t get it to recover. I’ve rebooted several times and there are no active chains.

This was coincident with me playing around with audio feedback routing in Patchage. So I cleared the chain by setting the system option to no longer start with the last state. Nothing helped.

I then tried the same IP address only I used the vnc_lite link. That works.

What’s the difference between the two vnc links aside from the obvious lack of the VNC sidebar? I couldn’t find any reference to vnc_lite on the forum.

However the normal link just results in the error below.

noVNC encountered an error:

Cannot read properties of null (reading ‘addEventListener’)
TypeError: Cannot read properties of null (reading ‘addEventListener’)
** at Object.addClipboardHandlers (**
** at Object.start (**
** at**


I hadn’t noticed vnc_lite before, thanks for pointing it out. The files says,

so probably one of those modules causing your issue. I’m traveling so can’t investigate now.

While we’re on the topic of VNC weirdness… I’ve noticed that the Zynthian UI image becomes horizontally distorted at times. The moving Zynthian logo can become heavily corrupted while loading a snapshot but other areas get corrupt as well. Notice the “Presets” and “Next Chain” buttons below.

Any idea what causes this? Incompatible refresh rates? Compression artifacts? None of that seems to make sense considering the much more complex VNC Engines display never gets corrupted.

Don’t bother looking into it. Turned out to be some garbage in the browser cache. I was accessing the Zynthian VNC via Chrome on ChromeOS which normally works great but even with multiple refreshes it would not get past this error until I blew out the browser cache.

I still would like your opinion on these VNC graphic distortions.

Screenshot 2022-11-27 20.40.05

The screen distortion is an annoying vnc effect. It relates to the data compression. I have on the past been able to get good vnc image but forgot how. I now suffer this bit out is bad and someone might want to investigate the cause and possible fix.

I have the same problem on my laptop even after clearing the cache (and with a fresh browser install). The problem is even worse in a table where the image is so corrupted that you cannot even see what is happening.