I just had the same issue and worked through it with tech support. We took our cleaning cartridge, popped it open at the brackets on the bottom, and took the cleaning fluid pouch, tube & nipple out. Then we took our #5 (white) cartridge apart the same way...disassembled it internally, drilled a small hole in the front of the cartridge to accommodate the bulk ink tube, put it all together and it all worked perfectly. We had initially confirmed that the machine itself was reading the cartridge by inserting the cleaning cartridge and not receiving the error; that's when we did the filleting of the cartridges.
So of course now we don't have a #5 cleaning cartridge, but we'll cross that bridge when we come to it.
By the way, while we had the white cartridge apart, with the tube and nipple in the open air, I dropped them into a cup with a bit of cleaning solution just to keep those ends moist and pliable. When we put it all back together I did a couple of head cleanings and we were on our way. Good fix!!