I was trying to change my wallpaper but I keep getting the message "can not set wallpaper from sandboxed process."
What I did was click the Picotron menu at the top left > System Settings > and then the wallpaper section under the desktop tab. This is without any custom wallpapers, trying to switch between the default ones.

Whenever I click a wallpaper it shows the error message. It only gets applied after a reboot.

Adding:
It happens on both my Windows 10 Desktop and Windows 11 Laptop.

I was having the same issue (on win 11 host) until I applied a nasty picotron OS hack I can't recall right now. I think the problem is likely a release bug.

If you'd like my hack I can look up what I did and provide instructions. It involved disabling some kind of version security check in the system drive (though windows via C:/Users/(..)/AppData/Roaming/Picotron/drive/system/).

That being said, I suggest waiting for the next official release. I've had a few sporadic crashes here and there, probably due to this hacky fix.

Thanks @SnappishOrc -- this is fixed for 0.2.1c