I wanted to update Audacity, but the 2.1.2 version (from the official download site) wouldn’t run: I got can’t open application Audacity.
There were lots of suggestions (for example here) but no joy.
I looked in the Console log:
14/08/2016 11:39:44.343 Finder: spawn_via_launchd() failed, errno=111 label=[0x0-0x2d52d5].net.sourceforge.audacity path=/Applications/Audacity/Audacity.app/Contents/MacOS/Audacity.sh flags=1
I looked for spawn_via_launchd() failed, errno=111 and found this which recommends reinstalling OS X (or should that be "macOS" now?), which seems a bit drastic. Another suggestion there is to repair the disk permissions, which Disk Utility won’t do any more; you can do it from the command line. I tried that, no luck.
Finally, I thought of open -a, and (because it’s a permission problem) sudo:
sudo open -a /Applications/Audacity/Audacity.app
This failed because the application isn’t recognised by Gatekeeper, so off to System Preferences / Security & Privacy / General and (temporarily!) Allow apps downloaded from anywhere.
And now I can run Audacity as myself!