Cannot be opened because it is from an unidentified developer

I am enjoying the most recent MPU episode on Preview but I have a consistent issue with it. I frequently get this message: . . . cannot be opened because it is from an unidentified developer. I have Googled and know that I can set it to open anyway in system preferences but that only lasts a little while. It is SO weird that I would get that message from system application. On the other hand, PDF Expert opens each and every time.

(I have searched the forum with several key words and didn’t find a solution).

You 100% should not be getting that message from a system application. It makes me think you might have something wrong with your installation of macOS.

The way that I usually handle 3rd-party apps that say this is by holding down the
Control key and then choose “Open”.

That should give you an option to open it “anyway”.

If this problem persists, I would recommend a clean installation of macOS, because something has gone “wonky”.

I have had this issue for several iterations of the OS. I will try your solution but the thought of doing a clean install will need to wait unti the end of the semester!