The update was supposed to report remaining charge level more accurately for Nikon's EN-EL14a lithium-ion battery, however some users have found that it has caused incompatibility with third-party batteries
Users of the Nikon D3100, D3200, D5100, D5200 and Coolpix P7700 have been affected by November’s firmware update, which has unexpectedly rendered third party batteries incompatible, as well as making it impossible to use Nikon batteries in third-party battery grips.
The update was claimed to simply improve accurate detection of remaining life for Nikon’s EN-EL14a battery, as well as generally improving battery performance.
Some users have reportedly managed to downgrade from the firmware, though this is a risky procedure that we wouldn’t recommend unless you’re confident you know what you’re doing.
Nikon are yet to comment on the issue.