Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 507)

507
Troubleshooting Guide
The camera cannot be used with EF-S or EF-M lenses (p.59).
Install a recharged battery in the camera (p.42).
Make sure the card is properly inserted (p.49).
If the card is full, replace the card or delete unnecessary images to
make space (p.49, 386).
If you try to focus in the One-Shot AF mode and the focus indicator
<
o > in the viewfinder blinks, a picture cannot be taken. Press the
shutter button halfway again to refocus automatically, or focus
manually (p.62, 145).
If a card error message is displayed, see page 52 or 525.
CF cards with a capacity greater than 128 GB and CFast cards are
formatted in exFAT. This means that if you format a card with a
capacity over 128 GB with this camera and then insert it into another
camera, an error may be displayed and it may not be possible to use
the card.
Shooting-Related Problems
The lens cannot be attached.
The viewfinder is dark.
No images can be shot or recorded.
The card cannot be used.
An error message is displayed when the card is inserted
in another camera.