Can’t update Retrobatch (Mojave 10.14.6)

I have Retrobatch 1.3. When I select “Check for Updates” I get an error:

Update error! Retrobatch can’t be updated, because it was opened from a read-only or a temporary location. Use Finder to copy Retrobatch to the Applications folder, relaunch it from there, and try again.

Only it is in the Applications folder; specifically, the all-users Applications folder. The Retrobatch app itself is set to be read-write by all user classes. The Applications folder itself is read-write by user and group, but is read-only for everyone else, and I can’t change it, even via sudo. (Unable to change file mode on Applications: Operation not permitted.)

Other applications in the same Applications folder don’t have a problem updating; for example, I just now updated Screenflick, which has even fewer write permissions than Retrobatch does.

What, if anything, can I do to fix this? Or should I just download the latest manually and hope copying it over top of 1.3 doesn’t mangle my registration info?

This is a bug in MacOS that crops up from time to time. There’s a little bit set in the app when you download it which tells MacOS to pretend it’s in a another volume, which keeps random downloaded apps from doing nefarious things. Later when the app is moved from the Downloads folder to the Application (or any other folder) the bit is supposed to be removed. Of course, sometimes it isn’t, and that’s the bug, and then Retrobatch thinks it’s on a read only volume because that’s what Mac OS is telling it.

There’s a couple of ways to fix this.

  1. Move Retrobatch to the Desktop folder, launch it, quit, and move it back to the Applications folder. This will hopefully nudge Mac OS to remove the bit.

  2. Re-download Retrobatch. Your preferences files will be maintained, so there’s no worry about that. Hopefully Mac OS will do the right thing this time.

  3. You can also manually get rid of the bit using the following shell command:
    xattr -d com.apple.quarantine /Applications/Retrobatch.app

Bonus points: if you wanted to see if it’s there in the first place, you could use:
xattr -l /Applications/Retrobatch.app

Let me know if that does the trick or not!