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error HP
Error Code Er/11
Cartridge improperly seated or possibly empty — insufficient connection or incorrect positioning of ink cartridge.
? What Causes This
Weak electrical contact from poor seating, cartridge is too low on supplies.
✓ How to Fix It
Refer Setup Guide’s detailed instructions for correct installation after checking printer’s current status and cartridge quantity availability.
Source: page 2 of the official manual
From the manual
This error code appears in:
HP Laserjet Mfp M139e M142e Printer