An information processing system includes a first control unit including a first memory configured to store first software, and a first controller configured to perform processing based on the first software and to update the first software in a case where an instruction to update the first software is received, and a second control unit configured to be coupled to the first control unit, the second control unit including a second memory configured to store second software that is the same as the first software, a second controller configured to perform processing based on the second software, and a first power supply circuit configured to start power supply to the second controller in a case where a failure in the first control unit is detected.