Canon Printer Error E56 — Data Transmission Error

What Does This Error Mean?

Error E56 means the printer received corrupted or incomplete data while processing a print job. This is most common with large files, complex PDFs, or when printing over a slow Wi-Fi connection. Cancelling the current job and resending it — or converting the file to a simpler format — usually clears the error.

Affected Models

Canon PIXMA MG5720
Canon PIXMA MG6820
Canon PIXMA TS8020
Canon PIXMA TR8520
Canon PIXMA TS9120

Common Causes

The file being printed is very large or complex and the data transfer was interrupted
A weak or unstable Wi-Fi signal caused packet loss during wireless printing
The print job was sent multiple times and conflicting data is sitting in the print queue
The document contains embedded fonts, layers, or transparency that the printer driver cannot process
A USB cable fault or momentary disconnection interrupted the data transfer mid-job

How to Fix It

Open the print queue on your computer and cancel all pending print jobs.

On Windows: go to Settings > Bluetooth & devices > Printers > your Canon > Open print queue. On Mac: System Settings > Printers & Scanners.
Turn the printer off, wait 30 seconds, and turn it back on.

This clears any corrupted data from the printer's internal memory buffer.
Restart your computer and try sending the print job again.

A computer restart also clears the print spooler, which can contain stale job data.
If printing a PDF, try printing it as an image instead — in the print dialog, look for 'Print as image' in the Advanced options.

Complex PDF layers and transparency are a known cause of data errors on consumer inkjet printers.
For Wi-Fi printing, move the printer closer to the router or connect via USB to rule out signal issues.

Wi-Fi packet loss during large transfers is a common and easy-to-overlook cause of E56.

When to Call a Professional

E56 is a software or connectivity issue — professional hardware service is not needed. If E56 occurs on every print job regardless of file type, reinstall the printer driver. Persistent E56 on USB connections may indicate a damaged USB port needing service.

Frequently Asked Questions

Does E56 delete my document?

No — E56 only means the print job failed. Your original file on the computer is untouched. Simply clear the print queue and resend.

I print the same file every day — why did E56 suddenly appear?

A change in file size, a Wi-Fi network issue, or a recent driver update can trigger E56 even for familiar files. Check that your Wi-Fi signal is strong and try reinstalling the printer driver.

Will upgrading to a newer Canon printer prevent E56?

Newer Canon models have larger internal buffers and faster processors, making data errors less likely. However, E56 from a weak Wi-Fi signal will still occur regardless of the printer model.