Hi, I've been using Thunderbird on Windows and Linux for years, and I'm very happy there. I just bought a nice Chromebook with an i5, 16 GB RAM and a 256 GB SSD. Chomeos installs a container of Debian Linux 11 and supports flatpak apps too. I've tried using the debian apt install thunderbird and the Flatpak version too. Mostly 115.*. I can't get any extensions to install directly, or after downloading the .xpi file. Thunderbird never lets you click on the last button to get the extension to install. Thunderbird must be force closed. So, my success has been to choose debug extensions, and install the file as temporary. THIS WORKS! The extensions load and operate perfectly. The downer is I'm having to re-install the temporary addons every time I run Thunderbird. I'm willing to do some extended troubleshooting, debugging, upload logs, pics, whatever you folks need to provide a solution for this. I'll install whatever beta/daily versions there are in order to get this resolved for everyone with a Chromebook. It seems there are lots of other folks with Chrome OS Linux that can't load extensions. It is "technically" I think a Linux virtual machine or as they call it a container. I have lots of other Linux apps running happily. Libre Office runs great, as do video editors, etc... I'm even willing to do a screencast video reproducing the problem. I'll do that later on. I'll post a link to the video so experts can watch exactly what happens. A 2 minute video is often better than text. If anyone wants to do remote debugging, or connect, or have me set up adb debugging I will do that also. Anyway, let me know exactly what additional information is needed. I'll post a short video in a bit. Thanks.