QR code not scanning? Find and fix the problem
First check what fails: does the camera see no code, does it read a link that will not open, or does it read Wi-Fi details but fail to connect? Each needs a different fix. A larger print cannot repair a broken destination.
Use this guide for menus, posters, labels, business cards and guest Wi-Fi cards. You can diagnose an existing code before deciding whether to replace the artwork.
1. The camera does not recognize the QR code
Try the original downloaded image on another screen, then compare it with the printed copy. If the original works and the print fails, concentrate on the print or placement. If neither works, simplify the artwork and try a plain code.
- Restore the clear margin. Leave a blank border at least four modules wide on every side. Modules are the small squares in the code. Keep text, frames and other graphics outside that border; do not crop it off when placing the download in your layout. DENSO WAVE specifies this four-module quiet zone.
- Use sharp artwork. Export SVG for a scalable print layout, or a high-resolution PNG. Avoid screenshots, stretching one axis, or enlarging a small raster image until its edges blur. Keep the code square.
- Improve contrast. Start with dark modules on a plain light background. Remove busy artwork behind the code. Test a plain version without a centre logo to isolate design problems.
- Increase the printed size. There is no universal minimum that works for every phone, printer, material and distance. More data can mean more modules inside the same width. Make the actual code larger, print a proof, and test at the distance visitors will use.
- Check the placement. Try even lighting and move to avoid reflections. A fold, curved surface, scratch or glossy cover may interfere with reading. Test the code on a flat proof as well as in its final position.
- Try another phone. Use the camera or QR reader that your visitors actually use. If only one device fails, check its lens, focus and QR-reading settings before replacing a working print batch.
Calculate the grid and print dimensions, and download an A4 proof for a plain static link or text code. Print at actual size and measure the proof's 50 mm scale line. For a Qex dynamic code, use its existing short link in the calculator so the proof keeps the same redirect. Test the original download separately if it includes a logo or frame.
2. The QR code scans, but the page will not open
If the camera offers a URL, it has read the pattern. Copy that URL into a browser and check where the failure occurs. Only open links you recognize and trust.
| What you see | What to check |
|---|---|
| The destination returns an error or asks for access | Open the destination directly without signing in. Check for a typo, deleted page, restricted document or changed PDF link. Use a public page that visitors can reach. |
| A Qex page says the code is paused | Open the owning workspace, check the code's status and resume it if permitted. A safety review or account limit may need resolving first. |
| The link works on one network only | Check connectivity and try another network. A successful read does not prove the destination is reachable from every visitor's connection. |
| An old menu or wrong page opens | Check the destination saved for the existing dynamic code. After editing, allow about a minute, then scan the printed code again and verify the final page. |
| Another provider's redirect fails | Check that provider's code status and service. Creating a new Qex code cannot take control of the domain encoded in an existing print. |
For Qex, open your workspace, select the existing code and check its destination. A guest workspace depends on the original browser state until saved with email. If you saved it, sign in with that email. Do not create a replacement code just to edit a destination: the replacement has a different short link.
3. The Wi-Fi code scans, but the phone will not connect
A Wi-Fi QR contains network details rather than a website link. Check the exact network name, password, encryption option and hidden-network setting against the router. Try joining that network manually with the same details. The phone must be within range, and a guest portal can still require a separate sign-in step.
If the credentials changed, generate a new Wi-Fi QR card and replace the old print. A static Wi-Fi code cannot be edited remotely. Test the card on your visitors' devices before displaying it; a successful scan alone does not establish a successful connection.
Can I fix a QR code that is already printed?
An editable destination can be fixed without reprinting if you control its dynamic code. Update the existing redirect's destination and rescan the print. Dynamic codes depend on the redirect service continuing to operate.
A static code's encoded data cannot be changed. If it contains a website address you control, you may be able to restore that page or redirect that address on your own website. If you cannot control the encoded address or payload, you need new artwork. Damaged, cropped or unreadable print also needs replacing, even when its destination is editable.
Before ordering the replacement batch
- Use the final artwork and the intended paper or material.
- Print one proof at the actual size, keeping the full margin.
- Scan it on more than one visitor device in the expected lighting and position.
- Complete the task: open the menu, read the PDF, reach the booking page or join the network.
- For dynamic codes, save control of the workspace and test again after any destination edit.
These are troubleshooting steps, not a physical scanning benchmark or a guaranteed print-size recommendation. Keep a readable short address or another way to access essential information beside the code.
Editable menu code · Hosted PDF code · Business-card link · Print checklist