Must be miswired at the switch or at the AFCI.
Good catchYour green wire should be attached to a ground screw in the metal box, not the bracket ground screw ( unless you have it attached in both places).
Not the trip problem, but it needs correcting.
I do not see an anti-short bushing inside of the cable connector. Perhaps the neutral is shorted to the armorI installed a new circuit and a light off of it. the circuit is a 20 amp circuit on a AFCI breaker with an outside light on it. Whenever I turn the light on it flicks on and the breaker trips. I can't figure out whats causing it, any idea's?
a picture of the light wiring is included below