I’m using 5.4 and I just got this error today.
Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff
Managed to narrow it down to an actor component that had a bad reference in my blueprint. I had changed a Text array variable to a Data Structure array variable, which necessitates updating the related dependencies. While the engine is pretty good at alerting me when I have an invalid type connection, this one slipped through and I was somehow able to compile anyway without errors.
Long story short, check all your connections and make sure the in and out pins match type.