@Andreas_Hegenberg I just updated to 15.2, and I noticed this happen again when opening BTT from Spotlight... but then I tried opening BTT from the Applications folder, and it worked.
I tried Spotlight again, and I noticed that it was actually trying to open "A document being saved by Sparkle." Opening the actual application in Spotlight does open BTT successfully.
Seems like this has been an issue before:
Was this also my problem last month, I wonder? I can't be sure. I would have been trying to open it with Spotlight then, too. But I notice that today, I was only getting a single "damaged or incomplete" popup when trying to open BTT, whereas last month I was getting two (see screenshot from my last post).
Thanks for your help! I'm a massive fan of BTT.