The code worked yesterday and shows an advert today. What happened?

That is a QR service showing ads on free or lapsed dynamic codes. Your code has not changed; the link inside it now goes through their advert page. Paying them removes the advert, or you can make a code here that never carries one.

Can Scanlight take over a code another service made?

No. The short link inside that code belongs to the other service, and only they can forward it. What we can do is make you a new code that is tested, sized, and either static and permanent or tracked with a clear lapse policy.

How do I stop this happening again?

For anything that will not change, use a static code: it cannot be paused. For anything that might change, use a tracked code from a service that publishes what happens when you stop paying, and read it before you print.

My QR code stopped working after I printed it

If a code scanned last month and does not now, the pattern has not changed. Either the destination behind it has gone, or, far more often, the code was a dynamic code on a service that has paused it: a trial ended, a payment failed, or the plan was cancelled. Read the code with the checker below to see which.

First, work out what kind of failure this is

There are two very different problems that look the same to the person holding the phone. In one, the camera cannot read the code at all: nothing happens, or it takes ages. In the other, the camera reads it instantly and the link goes to an error page, a 'plan expired' notice, or an advert.

The first is a print problem: too small, too little contrast, no margin, a glossy surface. Those codes never worked reliably; you are just hearing about it now. The second is a service problem, and it is the one that appears out of nowhere on codes that worked fine for months.

If it reads but goes somewhere wrong

The code contains a short link owned by a QR service. When you stop paying, or a free trial ends, many services pause the link. Some send scans to a page selling their own product. Some show an advert first. Some return a plain error. Your printed code cannot be changed, so the service holds every copy of it.

Sign in to whatever service made the code and look for the code's status. Reactivating usually means paying. Before you do, read their policy on what happens next time, because it will happen next time.

If you would rather not depend on that service again, make a new code and reprint. A free static code here cannot be paused by anyone. A tracked code here has its lapse policy written on the pricing page: 30 days of grace, then a plain page, never an advert.

If it does not read at all

Photograph the printed code straight on, in good light, and put it through the checker below. It reports the contrast, the margin, and how big the code should have been printed for where it lives. The three most common findings are a margin that a designer trimmed, a colour that looked fine on screen but not on paper, and a code sized for a flyer that ended up on a poster.

Gloss and curves are the two causes a photo cannot show. Laminated codes reflect the room's lights straight into the camera; a matt finish fixes it. Codes wrapped around a bottle or a corner distort; keep them flat and small.

What to do about the batch you printed

If the code reads and only the destination is wrong, and it is a tracked code you control, change the destination and every copy is fixed at once. That is the whole point of a tracked code.

If the code is static and the destination moved, the printed copies cannot be updated. Put a redirect at the old address if you control it: an old page forwarding to the new one rescues every copy. If you do not control it, reprint, and make the replacement a tracked code so this cannot happen twice.

If the code does not read, reprint. Make the new one here so it is tested with a real scanner and sized for the place it is going before you spend on print again.

Check your code now

A photo or the image file. It is read on your device and never uploaded.

Step 1

Add a picture of the code

A photo of the printed code, a screenshot, or the image file you were given. It stays on your device.

Choose a photo or drop one hereOn a phone this opens your camera. You can also paste a screenshot.

Step 2

Where is it, or where will it go?

We work out how big it needs to be printed to scan from that distance.

Questions

The code worked yesterday and shows an advert today. What happened?: That is a QR service showing ads on free or lapsed dynamic codes. Your code has not changed; the link inside it now goes through their advert page. Paying them removes the advert, or you can make a code here that never carries one.
Can Scanlight take over a code another service made?: No. The short link inside that code belongs to the other service, and only they can forward it. What we can do is make you a new code that is tested, sized, and either static and permanent or tracked with a clear lapse policy.
How do I stop this happening again?: For anything that will not change, use a static code: it cannot be paused. For anything that might change, use a tracked code from a service that publishes what happens when you stop paying, and read it before you print.

More guides

What size should a QR code be?The rule is scanning distance divided by ten, adjusted for how much data the code holds. Work out the exact size for your code and where it is going.
Static vs dynamic QR codes: the honest differenceStatic codes contain the destination and work forever. Dynamic codes contain a redirect you can change and can be tracked. Here is what each actually costs you.
Why QR codes fail to scanSix reasons a printed QR code does not work, in the order they actually occur, and how to tell which one you have.
Do QR codes expire?A plain answer: a free static code never expires, and a trackable code only stops when the service behind it stops. Here is how to tell which kind you have, and what to ask before you print.