@Pablin_Drummer2 and @riotpopmusic (sorry, I didn’t get back to you earlier before)
I regularly empty the trash in the project’s pool and I never had any crashes on either version of Cubase (13 to 15). So, it could very well have something to do with corrupted preferences on your system which can cause all sorts of unexpected behaviour.
Since the backup project function does work but is definetly not ideal I would suggest to temporarily disable all preference folders. You can achieve this by simply adding an underline as a prefix. This way you can go back to the previous state without risking to lose anything. Important: It is necessary to disable at least 13 and 14 to make sure that corrupted preferences are not automatically migrated again to the new C15 preference folder.
You’ll find the preference folders here in case you don’t know (close Cubase first):
Press the Windows key + R and paste “%appdata%/steinberg”. Now, you will see a folder called “Cubase 15_64”. Rename this folder for the time being by adding an _ as a prefix like _Cubase 14_64 and relaunch Cubase. Cubase creates a new folder with the exact same name but with the original default settings.
If this doesn’t work you can close Cubase again, delete the new folder, remove the _ from the old folder and launch Cubase again. Everything will be back to the previous state.
Note:
If you want to preserve your key commands, plugin collection and other personalized settings you could create a Profile which you can reactivate at any time (profile files reside outside the preference folder). You can also do a backup and restore specific settings afterwards, too. Here’s a very handy function for Windows to achieve that.
Does this solve the issue?
I keep my fingers crossed that it’s just a matter of a corrupted preference folder 