Dirt or paper particles are stuck to the feed rollers. Clean them.
First, remove all paper from the front tray. Open the paper output tray. Hold down the Stop button until the Alarm lamp flashes seven times, then release. The rollers will rotate to clean themselves.
After they stop, close the output tray. Load one sheet of A4 or Letter-sized plain paper (or a commercial cleaning sheet) into the front tray. Open the output tray and its extension.
Hold down the Stop button until the Alarm lamp flashes seven times again and release. The printer will feed and eject the paper, completing the cleaning.
If that didn't work: If paper still doesn't feed after cleaning, the rollers may be worn. Contact Canon service.
Heads up: This cleaning wears the rollers. Only perform it when necessary.