@jjapes Just update mupen64plus via retropie-setup.

@twinparadox

Nice troubleshooting. These types of problems with RetroArch turn up often when 'Save Configuration on Exit' is enabled, so be sure to make those files your first port of call for any other inexplicable issues going forward.

Make sure you didn't inadvertently disable the "Run Command" option.

Thanks Buzz, you made me question the validity of my roms, I've managed to get this working now, thanks for your assistance.

@montanafury No worries. I'm no expert. Just trying to help. It can be a steep learning curve... but worth it.

@overlord73978 Your romset (game zip file) is not compatible with the emulator you are using. Most commonly this is because the the romset version does not match that required by the emulator. More details on what to do on your other thread but it's basically:
https://retropie.org.uk/forum/topic/2859/how-to-use-mame-with-retropie-help-guide

@overlord73978 You should have downloaded a complete set of roms that is labelled accordingly. For Mame4All you need roms from the 0.37b5 set. I am guessing that because you don't know, you just downloaded a few random roms and tried to launch them in a mame emulator? A common mistake and the path to great frustration. MAME requires patience and an accurate set of roms that match the emulator of your choice. You can verify the roms you have using clrmamepro. The best way to use MAME in an "enjoyable" way currently is to first choose an emulator - lr-mame2003 - then find a set of roms that is compatible with it, i.e. the 0.78 romset. Before proceeding, you should read this very carefully as it will demolish any confusion you may have......
https://retropie.org.uk/forum/topic/2859/how-to-use-mame-with-retropie-help-guide

Thanks for the help. That did solve it for running it myself but the python script still failed. I get

/opt/retropie/configs/all/autostart.sh: line 1: 3353 Terminated emulationstation
tput: unknown terminal "unknown"
'unknown': I need something more specific.
Error opening terminal: unknown.
Traceback (most recent call last):
File "/opt/retropie/supplementary/runcommand/joy2key.py", line 42, in <module>
curses.setupterm()
_curses.error: setupterm: could not find terminal

Then emulationstation proceeds to launch again.

In the end I got everything working by going back to RetroPie v4.0.2. I really do not care about having the latest version for this one as it is more of a novelty item than anything since I can launch games with cartridges.