A printer that starts a receipt and then stalls, jams, or prints blank near the end is a familiar frustration at a busy counter, and it's almost always one of a handful of usual causes.
The paper roll is inserted backwards
Thermal paper only prints on one coated side — inserted the wrong way round, the printer will feed paper but produce nothing, or fade out partway if the coating is only partially facing the print head.
Low battery on a portable printer
Battery-powered mobile printers often stall or print faint, incomplete jobs as the charge runs low, well before the device shuts off entirely — worth charging fully before a busy shift rather than waiting for a low-battery warning.
A connection drop mid-print
For Bluetooth-connected printers especially, distance from the device or interference can cause a job to cut off partway through — moving closer or reconnecting usually resolves an isolated incident.
The print head is dirty or overheated
Dust or residue on the thermal print head degrades quality over time, and heavy continuous use can trigger a thermal printer's built-in overheat protection, pausing or slowing printing until it cools.
The paper roll is nearly empty
Some printers detect low paper and stop mid-job rather than printing onto the bare roll core — check remaining paper before a job starts if a printer has been unreliable near the end of a roll recently.