Final Cut Pro crashes every time I try to open a project and/or its backups: Termination Reason: Namespace SIGNAL, Code 6 Abort trap: 6

I have been working on a particular FCP project for a few weeks. Today it suddenly crashed and won't open. Every time I try to open (either by double click in the Finder or opening manually from FCP menu), FCP crashes instantaneously. I receive a Problem Report that has the Termination Reason of Namespace SIGNAL, Code 6 Abort trap: 6. I have deleted FCP preferences, I have tried opening on a different computer. Nothing works. I have backups saved from a few days ago which also cause FCP to crash (with the same termination reason).