ℹ
info HP
Status LED blinking and both Ink Alert lights are on (very low ink)
Both cartridges are very low on ink.
? What Causes This
Very low ink levels in the cartridges.
ⓘ What This Means
Continue printing but ensure you replace both cartridge as soon as possible once quality becomes unacceptable. Press Resume button ( ), then proceed with replacement.
Source: page 6 of the official manual
From the manual
This error code appears in:
HP Deskjet Ink Advantage 2135 All IN One Printer