Heres one for you all to try.

At the op panel click the layout/edit tab then Booklet then Book > Booklet.. leave all defaults.. Click OK... put paper on right side of glass -> click START... add second piece of paper to left side of glass (simulating an open book)-> Click START -> Click scanning finished button.
Machine will start and feed paper, a Cf26f code pops up on the panel and the paper comes out blank.

Do you get the code?

I tried this on a machine without updating F/W and it works fine. I talked with tech support and they got the code also. It is now in their hands.

If anyone has a fix for this, please, post it or email me.

Thanx!

I have a 4050 getting a CF26F does anyone know what causes it

According to the firmware bulletin the cf26F was fixed after v 2.03B of the firmware, in v. 2.04A. I certainly hope you are running newer firmware than that. =^..^=