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error HP
Error Code LED blinking and both Ink Alert lights blinking
One of the ink cartridges is installed improperly or incompatible.
? What Causes This
Wrong installation or incompatibility with ink cartridge.
✓ How to Fix It
Install correct type and model of ink cartridge, make sure it's securely inserted.
Source: page 6 of the official manual
From the manual
This error code appears in:
HP Deskjet Ink Advantage 2135 All IN One Printer