The "one time validation code" isn't one time, it's every time. Getting very annoying. 

Every time I open Tbird, I have to re-type the new one time EveryTime validation code, that sends the EveryTime  validation code to my email address. And that process refuses to accept the code. Yes, I can type a 6 digit code. and I can do that under the 5 minute allowance.

Maybe it's due to the fact that I am transferring a old version, on a old desktop  (68.1.1 (32 bit) to a 64 bit machine/OS that was sort of a wee bit successful /w 146.0 (64-bit) Tbird.