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Canon Printer Keeps Showing Paper Size Error? Here's Why

Last updated: March 2026

The Canon printer paper size error is frustrating because the paper is clearly loaded and it's the right size. The problem is that Canon printers check the paper size in three different places, and all three must match perfectly. If even one setting is wrong, the printer refuses to print.

Let's walk through how to get all three settings aligned so your Canon printer stops complaining about paper size.

In This Guide:

  • How to set paper size on the printer itself
  • How to configure paper size in the print driver
  • How to enable bidirectional support for automatic detection
  • Why WSD printer ports cause paper size errors

Understanding the Three Paper Size Settings

Check these three settings and ensure they all match: the actual paper in the tray, the printer's paper size configuration, and the paper size selected in your print driver. Before fixing the problem, you need to understand where Canon printers check for paper size information.

The Three Settings:

  1. 1. Paper in the tray: The actual physical paper loaded in your printer
  2. 2. Printer settings: The paper size configured on the printer's control panel or web interface
  3. 3. Print driver settings: The paper size selected in your computer's print driver when you send a print job

Why This Causes Problems:

If you load Letter size paper but your printer thinks it's A4, or if you select A4 in the print driver but the printer is set to Letter, you'll get a paper size error. All three must agree.

Fix #1: Set Paper Size on the Printer

Press the Setup or Menu button on your Canon printer, navigate to Device Settings or Preferences, select Paper Settings, choose your paper tray, and set the paper size to match what's actually loaded. This tells the printer what size paper is in each tray.

For Printers with LCD Display:

  1. 1. Press the "Setup" or "Menu" button on your Canon printer
  2. 2. Navigate to "Device Settings" or "Preferences"
  3. 3. Select "Paper Settings" or "Paper Source Settings"
  4. 4. Choose the paper tray you're using (e.g., "Cassette 1" or "Rear Tray")
  5. 5. Set the paper size to match what's actually loaded (Letter, A4, Legal, etc.)
  6. 6. If available, also set the paper type (Plain Paper, Photo Paper, etc.)
  7. 7. Press "OK" or "Apply" to save

For Printers Without Display (Web Interface):

  1. 1. Find your printer's IP address (print a network status page from the printer)
  2. 2. Open a web browser and type the IP address in the address bar
  3. 3. This opens the printer's web interface
  4. 4. Log in if required (default username is often "admin" with no password)
  5. 5. Navigate to "Settings" or "Device Settings"
  6. 6. Find "Paper Source Settings" or "Paper Configuration"
  7. 7. Set the paper size for each tray to match what's loaded
  8. 8. Click "Apply" or "OK"

Fix #2: Update Print Driver Settings on Your Computer

Open Settings, go to Printers & scanners, click on your Canon printer, select Printing preferences, and set the Page Size dropdown to match your printer configuration. Now that the printer knows what paper is loaded, make sure your computer's print driver is sending jobs with the correct paper size.

Windows Steps:

  1. 1. Open Settings and go to "Printers & scanners"
  2. 2. Click on your Canon printer
  3. 3. Click "Manage" (Windows 11) or just select the printer (Windows 10)
  4. 4. Click "Printing preferences"
  5. 5. On the "Page Setup" or "Main" tab, find the "Page Size" or "Paper Size" dropdown
  6. 6. Select the same paper size you configured on the printer
  7. 7. Click "OK" to save as the default

Important:

Also check the paper size when you actually print. When the print dialog opens, look for "Properties" or "Printer Properties" and verify the paper size is correct for that specific print job.

Fix #3: Enable Bidirectional Support

Press Windows key + R, type "control printers," right-click your Canon printer, select Printer properties, click the Ports tab, and check "Enable bidirectional support." This allows your computer and printer to communicate in both directions so the printer can tell your computer what paper sizes are actually loaded.

Steps:

  1. 1. Press Windows key + R to open the Run dialog
  2. 2. Type control printers and press Enter
  3. 3. Right-click your Canon printer and select "Printer properties" (not "Properties")
  4. 4. Click the "Ports" tab
  5. 5. Find the checkboxes at the bottom
  6. 6. Make sure "Enable bidirectional support" is checked
  7. 7. Click "Apply" then "OK"

Why This Works:

With bidirectional support enabled, your computer can query the printer to see what paper sizes are configured. This helps prevent sending print jobs with the wrong paper size settings.

Fix #4: Avoid WSD Printer Ports

Windows sometimes installs Canon printers using WSD (Web Services for Devices) ports. WSD ports don't support bidirectional communication well and frequently cause paper size errors.

How to Check and Fix:

  1. 1. Open Control Panel and go to "Devices and Printers"
  2. 2. Right-click your Canon printer and select "Printer properties"
  3. 3. Click the "Ports" tab
  4. 4. Look at the checked port. If it says "WSD" anywhere in the name, that's the problem
  5. 5. Remove the printer completely from Windows
  6. 6. Reinstall using the Canon setup utility from Canon's website
  7. 7. During setup, choose "Standard TCP/IP Port" or "Direct IP connection" instead of WSD
  8. 8. Enter your printer's IP address when prompted

Fix #5: Reinstall or Update Canon Print Driver

Outdated or corrupted Canon drivers can cause persistent paper size errors. Installing the latest driver from Canon often fixes communication problems between your computer and printer.

Steps:

  1. 1. Go to Canon's support website
  2. 2. Search for your printer model
  3. 3. Download the latest driver for your operating system
  4. 4. Before installing, completely remove the old driver using "Devices and Printers"
  5. 5. Restart your computer
  6. 6. Install the new driver
  7. 7. During setup, configure the paper size settings correctly

Common Mistakes to Avoid

  • ✗Don't mix Letter and A4: These are close in size but different. Make sure you're using the exact paper size configured on the printer.
  • ✗Don't ignore the "Paper Source" setting: If your printer has multiple trays, make sure you're selecting the correct tray in the print driver.
  • ✗Don't use WSD ports: Always use Standard TCP/IP or USB connections for Canon printers.
  • ✗Don't assume "Auto" paper size works: Canon printers want explicit paper size settings, not automatic detection.

How to Prevent This Problem

  • ✓Label your paper trays: Put a small label on each tray showing what size paper it contains.
  • ✓Stick to one paper size if possible: Using only Letter or only A4 eliminates confusion.
  • ✓Always use Standard TCP/IP ports: Avoid WSD when setting up network printers.
  • ✓Keep drivers updated: Check Canon's website for driver updates every few months.

Still Getting Canon Paper Size Errors?

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Frequently Asked Questions

Why does my Canon printer keep asking for a different paper size?

Your Canon printer shows paper size errors when there's a mismatch between the paper size configured on the printer, the paper size selected in your print driver, and the actual paper loaded in the tray. All three must match exactly. The printer is trying to prevent you from printing on the wrong size paper, which would waste ink and paper.

What's the difference between Letter and A4 paper?

Letter paper (8.5 x 11 inches) is the standard in the United States, while A4 paper (210 x 297mm, or about 8.3 x 11.7 inches) is standard in most other countries. They're close but not identical. If you load Letter paper but your printer is set to A4, you'll get a paper size error because the printer detects the size difference.

Why doesn't my Canon printer auto-detect paper size?

Canon printers can detect paper length but not width using sensors in the paper tray. This means they can't reliably auto-detect all paper sizes. That's why you must manually configure the paper size settings on both the printer and in the print driver. Some newer Canon models have better auto-detection, but it's still more reliable to set it manually.

What is a WSD port and why should I avoid it?

WSD (Web Services for Devices) is a Windows networking protocol that allows automatic printer discovery and installation. However, WSD ports have limited bidirectional communication, which means the printer can't properly tell Windows what paper sizes are loaded. This frequently causes paper size errors on Canon printers. Use Standard TCP/IP ports instead for better communication.

Can I use different paper sizes in different trays?

Yes, most Canon printers support different paper sizes in each tray. You must configure each tray's paper size individually on the printer itself (via the control panel or web interface). Then, when you print, select the correct paper source in the print dialog. Make sure the paper size setting matches the tray you're selecting.

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