How do I solve the “Red X Cartridge error” on my Epson x890, x900 printer?

This error is often caused by the cartridge’s exit funnel sensor detecting micro air bubbles.

Epson service manual (p.226 to 229) recommends blowing in the cartridge to increase pressure and releasing some of the ink using a paper clip. We've found an easier solution that consists of gently tapping the cartridge on a hard surface in different directions to move the air bubbles out.  See attached video.

Aware of this issue, Epson released firmware with wider tolerances to micro air bubble detection.  Therefore, upgrading to latest firmware level is recommended.  See “firmware upgrade” topic covered above.