Lost all sound output

[honestone]

One other thing that should be mentioned is Onyx. Last year, by the time I upgraded to High Sierra in December 2017, Titanium Software had gone through 3 iterations of Onyx for High Sierra before finally settling on a stable version. This year, they have already released Mojave versions of Onyx twice, and a third one is in beta testing:

https://www.titanium-software.fr/en/onyx.html

Again, I don't know if that is pertinent to your issue, but it is worth mentioning.

 

[honestone]

Yesterday, I resurrected an "older" Hitachi 2.5" 5400 rpm 160 gig SATA drive, installed it inside a new slim external enclosure (with USB 3.0 connectivity), and had Disk Utility Erase and format it (MacOS Extended, GUID Partition Map). I then downloaded Mojave, V10.14, from the AppStore, did a clean, fresh, "virgin" installation of it onto that external drive, and "migrated"/copied needed "stuff" from my most recent SuperDuper! backup (done this last Saturday). I then restarted my Mac Mini from that external drive. It was quite S...L...O...W..., understandable given that 1) it was via a USB 3.0 connection, and 3) the 5400 rpm speed of the drive is quite slow. But eventually it got to the desktop. I launched Thunderbird, and it worked fine. I did not need to enter/re-enter the password for the Incoming Server and Outgoing Server. It worked as normal. Also ran a few applications, and Mojave seemed fine. But due to how long it takes to boot up from that slow external drive, I erased and re-formatted the drive.

So, not sure why you would need to enter/re-enter the password for the Incoming Server and Outgoing Server. Did you check your Account settings? Mine migrated over without a hitch.