Mark III - Ocassional Err99

Finally had a permanent Err 99.

Camera's getting a new sub mirror box.

The error 99 on my old 10D got to be quite a hassle, so just before the third time I was going to send it back to Canon, I called to moan and groan about it. The tech suggested cleaning all the lens and camera contacts with an eraser before sending it back and by golly, that fixed it. Error 99 can be darned near anything, but if (probably when) I see it again, the first order of business will be cleaning contacts on everything with an eraser.

When my mirror does not move even in manual sensor cleaning mode, it's not the contacts.

Anke wrote in post #5723422
Looks like another trip back to Canon is on the cards, you'd hate for it to give the ERR99 when you have that crucial important shot in the viewfinder.
Perhaps clean all the battery and lens contacts to see if that works, but I'd send it back.

It turned out to be the mirror box giving problems. Canon replaced it and I have not had an Err99 since.