Error 20

Hi all I did a search for this topic "error 20", I did get some results but nothing concrete on the cause or indeed the repairs needed, just asking u all if any of you are aware of the definitive cause of this error code? Some think it's a card formatting thingy and other a mechanical failure?
Regards Philip

Oooops ment to say its my 5D MKII
Ta

When my 50d had that last year, I had to send it to canon to be fixed. I think they said it was the card reader malfunction. Cost me a little over $200.
But it was fixed!!!

Tks kdra......

The last (and first) time I got the Error 20 was with my 20D and a sigma lens. Correction: pull battery, unmount and re-mount lens, and re-insert battery. Power up and all was good .... never happened again. That was some 5 years ago. I doubt this helps a lot but it's the best I have.

Recently with 7d I have had to return to Canon the camera 3 times with error 20 problems. The internet seems to say shutter problem, sadly Canon have now got the 7d back for the 3rd time since November and I am multiply pissed off!!
Last time back it worked perfectly for about 35 shots before packing up refusing to do anything. The fact its back with Canon for the 3rd time doesn't say much for Canon's repair