Firmware version 1.116 for the Leica M9 includes a variety of performance improvements and bug fixes. Running the new firmware, the M9 provides a new ISO sensitivity-linked vignetting correction function, which applies strong correction at ISO 160 and gradually reduces the correction amount to its minimum by ISO 2,500 equivalent. The new M9 firmware also improves magenta color shift correction for the 18mm/f3.8, 21mm/f2.8, 24mm/f3.8, 28mm/f2 and 28mm/f2.8 lenses, and is said to offer higher quality thumbnails and faster zooming in playback mode. SD card formatting has also been sped up, and compatibility with a variety of SD cards improved, although the company still recommends use of only one of 23 different card models from ten vendors. and ranging in capacity from 512MB to 32GB (with SanDisk alone gaining over a third of the recommendations).

Issues that have been corrected include data transfer problems to Mac computers in USB Mass Storage class mode, a problem with sensor cleaning mode when battery life remaining is less than 50%, and incorrect behaviour when using the "Delete All Images" function with either a zoomed picture shown on the screen, or images from a camera other than the Leica M9 on the flash card. Leica has also corrected problems with zooming images captured using the Vintage B+W setting, incorrect Maximum Aperture Value information in EXIF headers when using a variety of lenses, and an issue when the camera was switched off during long exposure capture. A variety of incorrect menu texts in Chinese, English, and Japanese menus have also been fixed, along with certain other unspecified bugs.

The firmware update, instructions for its application and more details on the changes made can be found on the Leica website.