Canon MG7700 Series Online Manual page 860

1310
Cause
Size of paper may not be compatible with automatic duplex printing.
What to Do
The sizes of media suitable for auto duplex printing are A4, Letter, A5, B5, and postcard. Make sure paper
of the correct size is loaded. Tap OK on the touch screen to eject the paper and restart printing from the
front of the next piece of paper. The reverse side of the ejected sheet is not printed.
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