Yubikey suddenly stopped working on Ubuntu

If you are on ubuntu and/or your web browser is installed via snap and you use yubikey or any other physical 2fa device, there is a chance that the key suddenly stops working. It might not be broken as there seems to be a bug in snapd v2.62.

I went to report it but someone has already done that (https://bugs.launchpad.net/snapd/+bug/2062148)

The solution is to downgrade your snapd (at least at the moment).

Check what versions you currently have installed:

$ snap --version

If you are not currently using snapd 2.62, then you might want to stop and investigate the issue further (or downgrade nevertheless to eliminate snapd as culprit)

List available ones

$ snap list --all snapd
Name   Version  Rev    Tracking       Publisher   Notes
snapd  2.62     21465  latest/stable  canonical✓  snapd,disabled
snapd  2.61.2   21184  latest/stable  canonical✓  snapd

Note the revision numbers, in this case we want to use 2.61.2 with revision number 21184. Yours might differ.

Downgrade

$ sudo snap refresh --revision=21184

You might have to (however in my case it was not necessary) relaunch the affected web browser for this change to take effect.

Hope this helps!