Quick check first
- Hold the phone steady, 15 to 30 cm away, with the whole code in the picture.
- Make sure there is enough light and no reflection on the code.
- Try a second phone. If it works there, the problem is the first phone, not the code.
1. The code is too small
Rule of thumb: the width should be at least a tenth of the scanning distance, and never less than 2 cm. Print it larger or let people come closer. Details in the guide How big should a QR code be?
2. Too little contrast
Scanners need a clear difference between modules and background. Dark modules on a light background work best. Light pastel colors, yellow on white or grey on grey often fail. Inverted codes, light on dark, are not read by some older scanner apps.
3. The quiet zone is missing
Without a light margin around the code, the scanner cannot find its edges. Leave at least four modules free on all sides, and keep text and graphics away from the code.
4. The logo is too large
A logo covers part of the code. With error correction H about 30 % can be restored, but dirt and reflections use up the same reserve. Keep the logo at about 20 to 25 % of the width and never over the three corner squares. More in QR code with logo.
5. Too much content
Long links and full contact cards create dense codes with tiny modules. Shorten links, remove unnecessary contact fields or print the code larger.
6. Print or screen problems
- Blurry print because a small image was enlarged: use SVG or PDF.
- Glossy surfaces reflect light: use matte paper or film.
- Curved surfaces such as bottles distort the code: place it on a flat area or make it larger.
- On screens: turn up the brightness and show the code large enough.
7. The design went too far
Unusual module shapes, gradients and background images look great but reduce readability. Scanoli checks every design automatically and shows warnings. If the check fails, switch to simpler shapes or stronger colors, or lower the opacity of the background image.
8. The link does not work
Sometimes the code scans but the target fails. Check the address for typos, test the link in the browser and make sure pages, albums or forms are public. A common case: dynamic codes from other providers stop forwarding when a trial ends. More in static vs. dynamic QR codes.
9. The Wi-Fi code does not connect
Network name and password are case sensitive and must match the router exactly. Choose the correct encryption, usually WPA, and tick “Hidden network” if the network does not broadcast its name. After a password change, the code must be created again. All details in WiFi QR code.
Checklist before printing
- The readability check in the editor shows a green tick.
- Test with at least two phones, an iPhone and an Android phone.
- Print a test page at the real size and scan from the planned distance.
- Open the target on the phone and check that it loads quickly.
- Keep the original file (SVG or PDF) for later reprints.
