According to Canon, the update includes the following fixes:
First Allows the use of the central AF point to automatically focus when the camera is used with Objektiv-/Extender-Kombinationen whose maximum aperture combined 1:8 (1:5-6 without firmware update) is.
* For details on the lens and camera combinations, refer to the revised manual in the section on objectives and usable AF points.
Second Shows during the auto focus in AI Servo AF, the viewfinder information (such as the AF frame, the grid, etc.) in red.
* The AF can be confirmed easily when shooting in AI Servo AF, and in dark places.
* The lighting of the viewfinder is in AI Servo AF, periodically and not continuously.
Third Fixes the problem that the measured value of the AE sensor is not correct and that the captured image will appear black, depending on the lens attachment.
4th Fixes the problem that while the AEB shooting the error Err occurs 70th
5th Corrects errors in the menu screen in Arabic.
6th Fixes the problem that the firmware update for the lenses is not functioning normally.
The firmware update is available on the Canon website