Adobe has tested running the latest versions of Lightroom CC 2015/Lightroom 6 with macOS 10.12 (Sierra) and found no significant issues.

Adobe recommends that customers update Lightroom to the current version prior to updating to macOS 10.12 (Sierra). Adobe also recommends that customers do their own testing on a nonproduction partition to ensure that the new macOS works with their current hardware and drivers.

If you do encounter issues that are not already documented, feel free to report them on our feedback site.

Adobe has discovered the known issues listed below when running Lightroom CC 2015.8/Lightroom 6.8 on macOS 10.12 (Sierra).

• Lightroom 6.8: When you import photos multiple times from an SD card, sometimes the duplicates are not detected properly. As a workaround, do any of the following:
  • In the Import window, select the SD card displayed under the Files section on the left. 
  • Close and open the Import window.

Known issues in Lightroom CC 2015.7/Lightroom 6.7

Adobe has discovered the known issues listed below when running Lightroom CC 2015.7/Lightroom 6.7 on macOS 10.12 (Sierra).

• Lightroom 6.7 and earlier: On macOS Sierra, while importing images from iOS devices into Lightroom, you may face a random crash.

Known issues in Lightroom CC 2015.6.1/Lightroom 6.6.1 or earlier

Adobe has discovered the compatibility issues listed below when running Lightroom CC 2015.6.1/Lightroom 6.6.1 and earlier on macOS 10.12 (Sierra).

• Lightroom 3–5: Canon, Nikon, and Leica tethering do not work.
  
• Lightroom 3–6.6.1: The Import dialog box doesn't display Apply During Import and Destination options.
  Note: This issue persists if you update to Lightroom CC 2015.7/Lightroom 6.7 from the previous version already running on macOS Sierra. Right-click any of the right-side panels and select the Apply During Import and Destination options to make them visible in Lightroom CC 2015.7/Lightroom 6.7.  

• Lightroom 2–6.6.1: The message Modify Exposure with +/- keys is displayed every time Lightroom is launched
  
• Right-clicking a panel and choosing the option to show/hide the panels displays an error message. This issue can occur in all the Lightroom modules.
  
• In the Library module, clicking the Make or Model fields in the Metadata panel throws an error message, which may cause Lightroom to crash.
• Lightroom 3: Direct camera connections not detected by the Import dialog box (workaround— use a card reader).
  
• Lightroom 1–5: Cosmetic sliders issues
  

Solution

To avoid these compatibility issues on macOS 10.12 (Sierra):

• Update to Lightroom 2015.7/Lightroom 6.7,  or
  
• Remain on your current Mac OS X version and do NOT update to macOS 10.12 (Sierra) if you are running Lightroom 5 or earlier.