Debugging “XXX is damaged and can’t be opened. You should move it to the bin”

I’ve had this error happen twice and Apple is not very helpful in telling you why it’s damaged. It’s very hard to debug. These steps might help:

  1. Is the application signed? It probably needs to be signed.
  2. Alternatively, this error message can appear if the application is partially signed but some of the files have been modified. You can use codesign to see what’s going on:

    codesign -d -vvvv --verify