My D100 shows a displayed shooting error of "F EE". Shutter will not release.
I have confirmed the minimum aperture is set and the lens is seated to the body.
In field diagnose includes removing and replacing the: card, battery and lens. Powering off and on several times too. Swapping the card and battery with spares.
ONLY after either installing a different lens OR reinstalling the 80-400 about 25 times does the problem fix itself until whenever, at the worst time.
Have checked all pin connections in the camera and the lens. Cleaned the above mentioned contacts too. Note the mounting surface to lens has zero play/wear.