Short answer
The most common causes are an expired dynamic-code trial or subscription, a broken destination link, damage or glare on the print, poor contrast, a missing quiet zone, printing too small, or a sticker placed over the code.
If it scans but opens the wrong page
- Trial or subscription ended. The provider now redirects to a sign-up or error page. See do QR codes expire?
- The destination changed. The website moved or the page was deleted.
- Someone covered it. A sticker overlay sends people elsewhere. Check the physical code.
If it will not scan at all
- Low contrast or a light code on a dark background.
- No quiet zone: design elements crowd the code.
- Too small for the distance people scan from.
- Glare from glossy laminate or glass.
- Damage: scratches, folds, fading.
Diagnose in a minute
Paste the link or upload a photo into the QR safety checker. It shows the full redirect chain, so you can see whether the code dies at the provider, the website, or somewhere unexpected.
See which QR code generators keep codes working after you stop paying, with each provider's own terms.