From Canon:
Affected Product
EOS 6D Digital SLR Cameras
Details
Firmware Version 1.1.6 incorporates the following fixes:
Please note: After the firmware update has been performed the following setting will be reset to default.
Menu > Custom Function> C.Fn II: Autofocus > AF Microadjustment> 1: All by same amount
When updating the firmware of the camera, please review the instructions thoroughly before you download the firmware.
Support
Download Firmware Version 1.1.6 for the EOS 6D Camera
Thank you,
Customer Support Operations
Canon U.S.A., Inc