"File" NOT "App"... can't be opened because it is from an unidentified developer
got an mp3 via email from a musician friend of mine today. when i try to open it (in any app... itunes, quicktime, vlc, etc), i get this message as if it's a new Application that i just downloaded from the internet.
i KNOW what to do if it's an app (keep my system prefs security settings & secondary-click on it & choose open that way) that i trust, but i've never experienced this happening before with "Files" that i trust.
is this normal & safe to open as if it was an app? or could something have happened to it & opening could be bad? or could it have been intercepted & actually be some sort of trojan or something?
I had the same problem just now after I right-clicked on a file and changed the application it opened with using "Open With > Other..." and then selecting the application. The problem was solved when I right-clicked on the same file, went to Get Info, and changed the application it opened with there using the dropdown menu and then the "Change All..." button. It's "more permanent," is how I conceptualize it.
I should say, it seems that I had to do the above for each file that I had tried to open after changing the app with "Open With > Other..." That is, I tried to open 2 or 3 mp3s with the new app after using "Open With > Other..." so I had to change the default app for each of those particular mp3s using Get Info. All other mp3s open just fine in the newly-default app.
I have two guesses:
- It is an application masked as an mp3 file. Yes, you should not open it.
- Mac OS X gives warnings "blabla downloaded from internet" for anything, not just apps downoaded from Internet. If you are sure the file is fine, play it back.
By the way, mp3 files must be able to play back by just quick previewing them (Space bar).
The file has been "Quarantined" by macOS. There are various situations where this can happen.
Consider wether the file might be malware, and delete it if so.
Otherwise, you can un-quarantine the file by right clicking on it and selecting "Open" - you will be given a warning, which you should read, then confirm you wish to open it from that dialog.
Alternatively to remove a large number from quarantine with the following at a command:
xattr -d com.apple.quarantine /path/to/file