Canon has issued a firmware update for the EOS C300 Mark II and Mark II PL cameras which adds support for EF-S 18-135mm f/3.5-5.6 IS USM lenses (due for release in late March, 2016). The new lenses will not work on previous firmware versions for the EOS C300 Mark II, but they will function properly on Canon’s EOS C500, C300, C100 Mark II, and C100 devices without any update.
CFast 2.0 cards cannot be used to perform the update; a SD/SDHC/SDXC memory card with 64MB is required. Please note: Once the firmware update is performed, the menu and custom picture settings will be reset. Menus and custom picture settings can be saved onto a separate SD card prior to performing the update, and then loaded onto the camera after the update has finished.
Click here to download the firmware update file onto your computer (PC and Mac OSX versions available). The downloaded folder will contain a PDF file with instructions on how to perform the update.