In T87687#1150062, @Robert Guetzkow (rjg) wrote:

Are you sure that this is the error message you're seeing and not AttributeError: 'Scene' object has no attribute 'denoising_store_passes'?

Please provide the exact command you tried to execute, as your instructions are contradictory. You described enabling/disabling of the denoising pass but your code example tries to enable the Mist pass.
The correct command to enable the Denoising Data pass for Cycles is described in this answer on Blender's Stack Exchange.