"Unsupported value type" Error on Linux
When using Linux, you may come across an error similar to this spamming your system logs:
Though seemingly harmless, it can take up a lot of disk space if left alone.
This appears to be a graphics issue, and I've found a couple ways to reproduce this error-spamming:
1. GNOME 3 and GNOME Compiz
Certain desktop environments can cause this error - for me, it was GNOME 3 and GNOME Classic (Compiz).
With this cause, the error would just be a constant spam no matter what was happening on the computer.
The solution in my case was to use Unity (Ubuntu) or GNOME Classic (Metacity). If those do not solve it I would recommend checking others out too.
You can get the classic GNOME environments (it comes with both Compiz and Metacity versions) from the gnome-session-flashback package.
2. Certain GUI Applications
Another way the error could spam is when using some GUI applications.
The error appeared for me when I was using the browser Brave. I found (using tail -f /var/log/systemlog) The error would spam when making mouse movements over page elements.
It's assumed this was because of the custom UI that Brave has - I could not find a way to stop it, and used an alternative browser.