I have a couple of D7200 bodies, and one of them sometimes will go into a Err state. It appears to happen when the battery gets low, and a freshly charged battery doesn't seem to help.
In the most recent event, switching the camera to manual focus, changing the program mode dial, and releasing the shutter appeared to fix the problem.
Nikon would only offer that I send the camera in for repair. My search showed posts on different Nikon bodies from the 2010-2012 era which had similar problems. Generally the fix involved cleaning lens contacts, or substituting other lenses. No one stated that the condition cleared spontaneously.
So the conclusion I came to is that there are several causes of "Err" and that it would be helpful to have a list of conditions which cause an Err on Nikons.
Has anyone seen such a list? Has anyone had an Err indication, and how did they resolve it?