!!
critical HP
Error Code Resume light ( ) blinking with Error icon ( ) and one or both Printhead icons ( ) blinking
Indicates a printhead problem.
? What Causes This
Malfunctioning or worn out printheads can trigger this indicator pattern.
✓ How to Fix It
Open and close printhead access door to reset. Replace indicated printhead if issue persists following HP support guide at www.support.hp.com
Source: page 2 of the official manual
From the manual
This error code appears in:
HP Ink Tank 315