Users have reported seeing the notification HP laserjet pro 400 79 service error. Users of HP printers may encounter this service error due to a factor. This could be due to a small defect in the printer. It can arise due to outdated software. Such an error is most likely to arise on HP LaserJet Pro 200, 400, 500, and other variants. There are several approaches for resolving this HP-service problem depending on the updates.