When attempting to open the `prince` executable on macOS Catalina, the operation fails with the following system alert by Gatekeeper:

> # "prince" cannot be opened because the developer cannot be verified.
> macOS cannot verify that this app is free from malware.

In order to run the command line utility, you need to open the Security and Privacy preference pane in System Preferences, select the General tab, and click "Allow Anyway".

Alternatively, you can run the following commands from Terminal to first remove any quarantine attribute applied by Safari when downloading `prince`, and then manually add a SecAssessment system policy label to the executable:

```
$ xattr -d -r com.apple.quarantine /usr/local/bin/prince
$ spctl --add --label "Approved" /usr/local/bin/prince
```

Doing this will change the system alert to a system prompt to confirm running the executable.

To avoid these workarounds, the developers of Prince should provide a new release that's notarized with Apple. For more information, see: https://developer.apple.com/news/?id=09032019a

Thanks, we will take a look at this.

I ran into this also. I believe it would deter a large percentage of Mac users. Until it's fixed I would suggest linking from the documentation to this thread, or copying the workaround instructions into the installation instructions.

If installed via Homebrew, you may need the following variation in order to approve the actual binary rather than the symlink itself:

```
xattr -d -r com.apple.quarantine "$(readlink /usr/local/bin/prince)"
spctl --add --label "Approved" "$(readlink /usr/local/bin/prince)"
```

Based on feedback from a team member that used this, it may still require approval via Apple's GUI one more time after this. I do not use Catalina to test this myself.

This may be something to get integrated into the `brew cask install prince` formula (https://github.com/Homebrew/homebrew-cask/blob/master/Casks/prince.rb) but I'm not sure if this is how the Homebrew maintainers would prefer to handle Catalina Gatekeeper stuff. [UPDATE2: I asked the Homebrew Cask maintainers this directly at https://github.com/Homebrew/homebrew-cask/issues/75897]

The path of least resistance would be to have the Prince developers submit to Apple's censorship process, as I doubt the latter would have any reason to block this particular utility.

Edited 21 Jan 2020 by natevw

Posting, again, with the caveat that I do not have Catalina handy to test this myself.

A homebrew-cask maintainer has replied to my question with a much simpler tip: apparently the workaround for this would be to use

brew cask install --no-quarantine prince

for the installation. Apparently it is Homebrew itself going out of its way by default to add the quarantine xattr for a bit of extra caution.

IIUC the quarantine part is only half the battle though, and the system policy for approving an unsigned app could still be a problem. So hopefully someone else can chime in with further tips for getting prince running under Catalina if they are needed.

Edited 21 Jan 2020 by natevw

I set up a new machine and had to reinstall. I was disappointed that the installation instructions for Mac still don't work, and still don't contain a link to this thread. But I'm glad that this thread exists.

As a Homebrew user, I confirm that natevw's instructions worked:

brew cask install --no-quarantine prince
prince --version

I spoke too soon. I also had to find the actual installation directory from Homebrew to replace the default license.dat with the one I purchased. In my case it was in /usr/local/Caskroom/prince/13.5/prince-13.5-macos/lib/prince/license

mj@mj-MBP license % pwd
/usr/local/Caskroom/prince/13.5/prince-13.5-macos/lib/prince/license
mj@mj-MBP license % cp ~/Downloads/license.dat .
mj@mj-MBP license % prince --version
Prince 13.5
Copyright 2002-2020 YesLogic Pty. Ltd.
Desktop License
mj@mj-MBP license %

We have now released Prince 13.6, which is suitably signed and notarised which should hopefully smooth out the installation process on MacOS!

I have a version 9 Prince and I don't know how to install it on M1 Mac...same problem as mentioned in this thread but all the commands listed here didn't work for me.

I would recommend installing a newer version of Prince as we have made many improvements and it should also be easier to install.