I just upgraded my laptop to Mac OS Catalina.

The Solarus app opens fine, but when I try to open my .dat file, I get the error "Cannot open file."

The file hasn't been moved, and I haven't deleted it—it's in the same place it's always been.

Has anyone else run into this problem? What was your fix?

UPDATE: I removed Catalina and went back to Mohave OS, and everything's working again. Still—wth?