The first time I tried to publish new images to Flickr, Lightroom aborted and the OS put up a dialog warning me that the app “magick” isn’t signed and so it might be dangerous, so the OS wouldn’t let it launch. “magick” is part of the ImageMagick graphics tool suite, a commonly used set of image manipulation tools; as of today the developers haven’t signed it with a developer certificate from Apple, so Apple’s Gatekeeper will reject it.
You can tell the OS to let the app run, but it’s not obvious where to do that. Here’s how:
Try to export some images and get the warning dialog. Then open up the System Preferences app and navigate to the “Security and Privacy” section and the “General” tab. At the bottom of that tab, you should see some text similar to the warning you got in the dialog. There’s an “Allow” button there. If you click it, you’re approving that app as something that’s okay to be launched.
When launching an app directly, the workaround is easier: you can Control-click and choose Open from the contextual menu.
In both cases, why doesn’t the alert tell you how to resolve the problem (if you do, in fact, trust the software)? In my view, this is poor design and essentially security through obscurity. Apple decided that they don’t want you to run unsigned software, but they don’t want to (or realistically can’t) completely forbid it, so they provide an escape hatch but keep it hidden. macOS doesn’t trust the user to make the right decision, so it acts as though there’s no choice.
The solution to these errors reminds me a little of the de facto standard for burying rarely-toggled options in hidden preferences set via the command line. It’s a pretty clever trick. But the dialog provides no indication that this is possible; it treats unsigned apps as inherently dangerous, not just a risk for the user to take. I know about the secondary-click-to-open trick, but I always forget it when I launch an unsigned app and get spooked before remembering how to proceed.
Perhaps this is the intention, but it makes security far too visible to the user and makes solutions far too opaque. The dialog is unhelpful for average users, and irksome for more technically-capable users. It’s not striking a good balance.
Descriptive error messages are useful; silent failures, misleading dialogs, and vague errors are not.