Why did my QR code stop working? (and how to fix it)
Dead QR codes usually mean a moved page, an expired generator, or a bad print. Diagnose in this order.
1. The destination page moved
Scan the code and read the URL your phone shows before it loads. If it's a page that now 404s, the code is fine and the page moved. A static code can't be fixed without reprinting; a dynamic code is fixed by editing the destination.
2. The generator expired
Many 'free' QR generators produce dynamic codes that redirect through the generator's domain and stop working after a trial. If the scan lands on a 'this code has expired' page, that's what happened. Recreate the code with a paid service that states its policy plainly, then reprint.
3. The print is unscannable
Too small, too little contrast, no white margin, glossy glare, or a damaged surface. Try scanning in shade with a different phone. If a fresh print of the same image scans, the problem is physical.
4. The link is too long
Very long URLs create dense codes that fail at small sizes. Shorten the destination or use a dynamic code, which encodes only a short redirect link.
Prevent it next time
Use dynamic codes for anything printed, keep the destinations in one place you control, and scan the physical print before you distribute it.