It’s shit - part of the problem - been deleting stuff and clearing space but not helped as now ableton has the critical error message and won’t even load. Annoyingly my backup also won’t work. The Mac has stopped allowing any peripherals or even iCloud or airdrop

OK. There may be some huge cache files in your library folder, even Ableton itself may be a culprit if there have been crashes that are writing huge amounts of data, like in /Users/[username]/Library/Caches/Ableton/Cache/ or in that area. Sort by size to find big files.

Is it weird that I can’t locate the cache?

Oh wait- hidden folder - got it. Thanks! It was packed full of

Will try this thanks.

Once you've freed up enough space, then make a new User and test ableton from there.