49 — firmware or communication error
This is the printer's firmware falling over, usually while chewing on a print job it couldn't process. Cancel everything in the queue, switch the printer off, unplug the network or USB cable, wait a minute, then power it back on with the cable still out. If it comes up clean, reconnect and send a simple one-page document before anything complicated. A firmware update fixes the recurring version, and an out-of-date driver on one computer is often what keeps triggering it.
Related codes: 49