can't open old 2.3.0 .aup files (can't find eff)

But the files are where they should be (same original folder, named properly). I’ve upgraded both OS (11.6) and Audacity (3.1.2) since last working on the files.

I saw other posts about editing file header text in a text editor. Will that help? What should I change.
Obvs it’s a directory issue, but not sure how to fix.


Audacity 3.1.2
MacOS 11.6 (Big Sur)