I have reviewed the posts from others that seem to have a similar issue and they were not the same situation. None of the posted solutions were issues that I appear to have.
I am getting this exception in my Crashlytics log ever since iOS 8 was released. I have reviewed my background fetch handler and had other developers review it as a sanity check. It does not appear that I am calling the completionHandler more than one time per background fetch call.
As a precaution, I put in a boolean to keep the code from possibly being re-entrant and that did not seem to change anything - not that I thought it would.
I have been unsuccessful in my attempts to recreate this issue on my devices or in the simulator.
Any help would be appreciated!