Unable to read the map .dmm

[Lonchadepavo]

Hello , I made a custom map a few months ago and yesterday I got the new code of tg and overwrote a map for mine, but it does not open the map.

(Sorry for my English, but I can't speak very well)

[JackHunt]

This is tough but not as bad as it could be. DM will still open maps with incorrect paths so it's not that. It's possible that a map item itself, such as a locker or spawner, references a missing item. Off the top of my head the shotgun change here: https://github.com/tgstation/-tg-station/pull/10019 will do it because they can be found in the old loot spawners. There might have been other changes over the past few months that will do it as well. Unfortunately if you haven't been following git closely they can be hard to find. If anyone can chime in with other map breaking changes, please do.

[Lonchadepavo]

Can anyone tell me if things have changed more ?

[Miauw]

unable to read the .dmm as just an error message means that DM has corrupted your map. Unless you have backups or use the past versions thing you probably lost it forever.
Always keep backups, DM is a piece of shit.