Comment 4 for bug 1871456

When I upgraded from Ubuntu 18.04 to 20.04, this happened.

Before upgrading I had one file on the desktop with a custom icon. After upgrading, the custom icon was no longer showing, and it showed a general-looking text file icon. When I right-clicked and opened its "Properties", it showed the icon, and if I clicked on the icon, navigated to the icon file, and clicked "open", nothing changed.

I went to Dash -> Tweaks (gnome-tweaks) and toggled the Extensions -> Desktop Icons to on, and I rebooted.

The custom icon still does not show on the desktop. After the reboot, I again right-clicked on the file, went to "Properties", and reassociated the file with its custom icon. But still, it doesn't show the icon on the desktop. As the original poster of this bug mentioned, it's possible to get the icon to show in the file browser.