From Canon:
Thank you for using Canon products.
Firmware Version 2.1.3.1.00 incorporates the following improvements and fixes:
Firmware Version 2.1.3.1.00 is for EOS C300 cameras with Firmware Version 2.1.2.1.00. If your camera’s firmware is already version 2.1.3.1.00, it is not necessary to update the firmware. Once the camera is updated to the latest firmware version, it cannot be restored to a previous version.
Support
Download Firmware Version 2.1.3.1.00 for the EOS C300.
For further details, please refer to the latest version of the instruction manual for this product, which will be released at the same time as this firmware update.
Download the new version of the Instruction Manual for the EOS C300 Cinema EOS Camera.
This information is for residents of the United States and Puerto Rico only. If you do not reside in the USA or Puerto Rico, please contact the Canon Customer Support Center in your region.
If you have not already done so, please register your Canon EOS C300 Cinema EOS camera. By registering, we will be able to notify you via email about future service upgrades.
B&H carries the Canon EOS C300 Cinema camera.