A QR code that won't open: where to start
A guest sits down, points their phone at the menu, and nothing happens. The screen shows an empty frame, or an error message. In the vast majority of cases, the cause is purely physical: a code that's too small, a dead link, a blurry print job.
Before you blame the phone, run the simplest test there is. Check that the code opens from another device, on another network. If a second phone opens it without trouble, the problem is with the first phone, not with the code itself.
- Test the code with two different phones, one Android and one iPhone.
- Turn off Wi-Fi and switch to mobile data to rule out a page blocked by the network.
- Clean the lens: a dirty camera can no longer pick out the black and white modules.
- Type the target URL into a browser by hand to confirm it still responds.
The 8 most common reasons a QR code won't scan
1. The code is too small
The rule of thumb comes down to a ratio: the width of the code should be about one tenth of the reading distance. A 2 cm code on a table tent just about works; the same code in a window read from 1.5 m never will. For a table menu, don't go below 2.5 cm square.
2. The contrast is too low, or inverted
A gold code on a cream background looks lovely and scans terribly. Readers look for dark modules on a light background. Avoid the reverse: many phones cannot read a light code on a black background, and plenty of codes can stop working overnight after a redesign.
3. The print quality is poor
An image exported at 72 dpi and then enlarged gives you bleeding edges. Codes printed from a low-resolution file are the number one source of complaints. Use a vector export (SVG or PDF), or a high resolution of at least 300 dpi.
4. The link behind the code is dead
The code scans perfectly, but the url returns a 404 error. This happens after a domain name change, a website rebuild or a deleted PDF file. If the code is static, it's frozen: the content can no longer be changed, so everything has to be reprinted.
5. The surface is folded, laminated or glossy
A gloss laminate bounces the spotlights straight back into the lens. The result: a scan that spins without ever locking on. Go for a matt finish, and avoid placing the code on a fold or in the corner of a tablecloth.
6. Too much data encoded
The more characters you encode, the denser the pattern gets. An excessively long URL, loaded with tracking parameters, produces a code that camera apps take several seconds to read. Shorten the link before you generate the artwork.
7. The code is shown on a screen
Tickets, kiosks, tablets: brightness and reflections throw the reading off. Turn brightness up to maximum and switch off dark mode. The same goes for codes sent by email, which the recipient scans from a second screen.
8. The code has expired or been deactivated
Many service codes have a short lifespan: a few hours for a parcel, a few minutes for a login. An expired code scans perfectly but no longer opens anything. Check the issue date before looking any further. If the principle seems murky, this article explains how a QR code works and why certain modules are essential to reading it.
When the phone is the problem: Samsung, Android and iPhone
«qr code not working samsung»: the settings to check
This is the most common search on the subject, with close to 90 queries a month. On Samsung, scanning goes through the native camera, but the option has to be switched on. Open the camera, go to settings and enable «Scan QR codes». If the option isn't there, use the shortcut in the notification panel.
On iPhone
Since iOS 11, the feature is built in. If it stops responding, open Settings, then Camera, and enable «Scan QR Codes». A restart fixes a good share of cases. Also try standard photo mode rather than portrait mode, which handles close focus poorly.
Out of fifty complaints from restaurant owners, only one came down to a fault in the code itself. The other forty-nine came from the medium: size, glare or print quality.
Why some QR codes work and others don't
Service codes follow their own internal rules. A parcel carrier or click-and-collect QR code is tied to one specific shipment and becomes invalid once the parcel is handed over. A gym membership code regenerates every time the app is opened and cannot be captured in advance. Same logic for school portals, resale apps, phone transfer tools or betting apps: the refusal comes from the server, not from the optics. In these cases, the only fix is to regenerate the code from the original app.
Static or dynamic: what changes when things break
No tool will claim to solve every printing problem you have, but the type of code determines how much room you have to manoeuvre the day the link goes down.
| Situation | Static code | Dynamic code |
|---|---|---|
| The link changes | Full reprint | Edited online, code unchanged |
| Mistake in the menu | Fixed at the next print run | Fixed in seconds |
| Pattern density | High if the URL is long | Low, faster to read |
| Scan tracking | None | Number of scans, times, device |
| Cost of a correction | Printing + installation | Zero |
That's exactly why an editable QR code menu saves you a reprint every time the special of the day changes. Your guests have nothing to install in order to scan it. They can open the menu straight from the camera, which noticeably improves the experience in the dining room.
How to check a QR code works before you print it
A five-minute check saves you throwing away an entire print run. The most demanding users are the ones who'll give you thirty seconds of attention at most.
- Print a paper proof at actual size, never a screen-only test.
- Test at normal range: arm's length for a table, two metres for a window.
- Run the test in low light, in the evening, when the room lighting is dimmed.
- Check that the landing page opens properly on mobile and shows the right information.
- Check it with two different apps, native and third-party.
A code can also stop working for certain customers only: that's the sign of a browser compatibility issue. Scan tracking and menu management tools then show you which devices the scan fails on, which helps a lot in narrowing down the cause.
Key takeaways
A QR code that won't respond almost always comes down to size, contrast or the link. Start with the printed medium, not the phone. A dynamic code lets you fix what's actually in use without reprinting, and it's also your best protection against an out-of-date menu in the middle of the season.
If the code belongs to a third-party service, regenerate it: that's quicker than hunting for a fault that doesn't exist. And always keep a paper menu in reserve for two tables out of ten.