Yes i was refering to the encore.sh file, if you check at the top it has a line pybin="python3"That determines the python version it will run when executed, i changed that one to "python2.7". 

To be clear, i was running "fp-05-firepower-cli", (which apprently is EOL since this year also) but reverted to "eStreamer-eNcore-cli-3.5.4". Had the same issue with cert, but solved with -legacy as well. Everything seems to be working fine with the ...

I got the same issue, getting the same errors (worked fine untill two days ago). I'm running Python 3.10.12.Havent done any updates/changes to either encore or FMC.