Canon 4496B008AA Advanced Manual page 387

Nineteen flashes:
An unsupported USB hub is connected.
the printer.
If you want to continue printing in this condition,
you need to release the function for detecting the
remaining ink level. Press and hold the printer's
RESUME/CANCEL
button for at least 5 seconds,
and then release it.
With this operation, releasing the function for
detecting the remaining ink level is memorized.
Please be advised that Canon shall not be liable
for any malfunction or trouble which may be
caused by continuation of printing under the ink
out condition.
Note
If the function for detecting the remaining ink
level is disabled, the ink tank is displayed in
gray on the printer status monitor.
Routine Maintenance
If a PictBridge compliant device is connected via a
USB hub, remove the hub and connect it directly to
the printer.
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