EOS device boots into a weird state - [PyServer ar.Aaa not responding, still trying -- is it running?]

One possible reason is that, there is an unknown registered toggle switch.....

Arista Networks EOS 4.22.4M
localhost login: admin
[PyServer ar.Aaa not responding, still trying -- is it running?]
[PyServer ar.Aaa not responding, still trying -- is it running?]

...<snip> reboot....

Welcome to Arista Networks EOS 4.22.4M

Failed(tg != toggles.end()) Toggle #BfdPeerDeferredDeletion not registered

.....

...reboot....

Press Control-C now to enter Aboot shell

...press ctrl-c here to enter aboot mode...

^CWelcome to Aboot.

Aboot# cd /mnt/flash

Aboot# mv toggle_override toggle_override.old

! get rid of /mnt/flash/toggle_override file

Aboot# reboot

....

.... now it is good....