(Why WebKit is used for the purpose remains a mystery to me. This last point matters because the Ubuntu MATE Welcome application (and even the Software Boutique, I think ) uses WebKit to display the fancy user interface of the Welcome application. WebKit, an HTML 'rendering engine' (core of a Web browser), is among the users of GStreamer multimedia files abound on the modern Web, and thus WebKit needs to support multimedia files in order to be competitive in the modern Web rendering engine arena. It's usually used by GNOME applications and their derivatives for multimedia decoding and encoding, usually the former to display / play video and audio files. GStreamer is a library which handles audio and video processing. If using Virtual Box please use VMVGA as your video adapter. If using KVM or QEMU Virtual Machines please use 'virtio' as your video adapter Login with your username and password and do the following: sudo apt-get purge gstreamer1.0-vaapiĬtrl + Alt + F7 will bring you back to the GUI Login and you can proceed as you would normally. Then the user can login to the machine and not have the possibility of this particular login crash loop. On the first boot after installation, before logging into the machine, drop into a TTY session login and remove the gstreamer-vaapi application. While this is being worked out, there are a couple of workarounds. It is possible for a user running Ubuntu MATE 20.04 in a Virtual Machine to come upon a login-crash loop. However, it is particularly troublesome for us as Welcome is one of the programs that this issue affects. This bug occurs with several programs and is not limited to Ubuntu MATE. Currently there is a bug in 20.04 that causes the desktop xorg session to crash and drop the user back to the GUI Login screen.

Fomm crashes on login