I run a 38.5ver portable app version of Thunderbird.
I've got it customized with a couple of addons, and use it occasionally on multiple computers in an IMAP configuration on all computers.
Today, it seem like it 'updated' something, but when I looked to the changelog for updates, for 38.5 the updates were from 2015. 3 things, two of which was a security fix, and some sort of 256 something compatibility with microsoft.
I've got 'check for updates' turned off. So what happened today?