I decided to finally upgrade from 1.3 to 1.4 on my computer today and ran into a few issues.
The first was fairly easy to handle, the usual notarization stuff.
But after that, Julia could just never seem to launch, often resulting in the following error or just hanging:
Perhaps this isn’t entirely Catalina related, as someone was able to verify that they encountered no such issues after upgrading:
So, any ideas?
It worked OOTB for me, so I have no clue unfortunately.
Are you running Julia by double-clicking the icon in the Finder? With all the changes in Catalina I think you might encounter problems this way that you won’t meet if you just launch Julia by typing julia in the Terminal (with a suitably configured PATH) or by launching Atom/Juno, etc.
Having used Catalina for a week now, I wouldn’t be surprised if something is asking for permission and you’re unable to see/confirm the dialog. I don’t have faith that any AppleScript will work reliably in these new conditions.
I’m also wondering why Catalina moves or copies the Julia-1.4.app from /Applications to /System/Volumes/Data/Applications/Julia-1.4.app?
Welp 1.3 didn’t have its path configured correctly OOTB, but seems 1.4 works just fine from the terminal. Guess I’ll just open an issue on GitHub for the double-click, thanks for the valuable suggestion!
What’s more interesting I think is that when I launched from Terminal I think all of the Julia instances that failed to launch suddenly sprung up, and following that the application started to work. Go figure.
Glad it’s working for you. Double-clicking the icon does work for me on 1.4… 
Let me repeat that, after one terminal launch I too can now double-click. No idea why.
