Unable to boot Raspberry Pi with Ubuntu 20.04

[flamethrow3r]

I've just tried a few different things, including using older start*.elf and fixup*.dat files, making other combinations of new kernel and other boot partition files and booting Ubuntu by installing it into the disk (SD card) from the Raspberry Pi OS desktop. However, nothing seems to work. Is anyone able to reproduce the issue or suggest some solutions?

[currentshaft]

4b

[flamethrow3r]

Yes; Ubuntu 22.04 doesn't cause any boot issues, but I need 20.04 for my project. I've left a link to the image in the original post.

[flamethrow3r]

So I managed to get Ubuntu MATE by installing Ubuntu Server 20.04 through the image built into the Raspberry Pi imager and then installing the desktop in there (through "sudo apt install ubuntu-mate-desktop"). However, I think it didn't turn out quite right: the password thing is on the left, with the MATE background behind it, although it does work. When you enter the password, the background turns into a blue screen and everything is extremely laggy. Even though I had connected to a Wi-Fi network to install the desktop, it doesn't find any networks anymore (opening the tab with the Wi-Fi symbol on top shows "device not ready" instead of the network options). It also installed GNOME as well, for some reason.
I did a reboot and the blue screen thing doesn't happen anymore. Still no network, though.
Edit: even though the network symbol appears as if I had no Wi-Fi, I seem to be able to use the internet with no problem.

[flamethrow3r]

I haven't had any more issues, so it seems the solution is to install Ubuntu Server 20.04 through the Raspberry Pi imager (not from the official downloads) and then install the MATE desktop there. I'm therefore marking this as solved.
It seems to be an issue with the official images, so they might need an update, or a fix. I'm not sure what exactly caused the issue, but I'll look into it if I have time in the future.