Two people stand at the same poster. The iPhone opens the page before its owner has the phone level. The Galaxy beside it sits in the viewfinder for fifteen seconds with nothing on screen. Both phones are current, both cameras are better than the code deserves, and the difference is not the sensor.
Android has no single scanning path, which the general iPhone-versus-Android case covers from the decoder side. Samsung is the sharpest instance of it, because One UI ships more than one scanner, has moved the switch controlling the main one between releases, and turns detection off in camera modes people routinely leave their phone parked in.
Five pieces of software, one code
On a current Galaxy, any of these can read the square in front of you.
The stock Camera app detects codes in the viewfinder and surfaces a bubble or a banner that you tap. The Quick Settings panel has a scan tile, which Samsung added years before Android itself grew one, so a recent Galaxy may carry both Samsung's tile and Google's in the same pull-down list. Samsung Internet has a reader reachable from its menu. Google Lens, which arrives with the Google app rather than with One UI, reads codes from the camera and from any image already on the phone. And any dedicated scanner app from the store does the same job with none of the version variance.
That is a strength and it is also where the confusion comes from. When somebody says their Galaxy will not scan, the first question is which of those five they tried, and the answer is almost always the camera and nothing else.
The camera scans in Photo mode and nowhere else
This wastes more time than any other cause and almost nobody knows it.
The Camera app's code detection runs in Photo mode. Leave the phone in Portrait, Pro, Night, Food, Panorama or Single Take, which is exactly what happens when the last thing you shot was a portrait, and the viewfinder will show your code beautifully and do nothing with it. There is no error and no hint. Detection simply is not running.
Check the mode strip along the bottom of the viewfinder before concluding anything else is wrong. Swipe back to Photo, point again, and a large share of "my Galaxy cannot read it" reports end there.
The toggle that moved, and then left
Samsung has shipped code scanning as an opt-in setting, as an on-by-default setting, and as a thing with no setting at all, depending on the One UI version, and the menu holding it has moved more than once. On some builds it sits in the camera's own settings. On others it is in the phone's advanced or useful-features section. On the newest builds the option is gone because scanning is always on.
Naming the exact path is how articles about this go stale within a year, so use the version-proof route instead. Open Settings and use the search field at the top. Type QR. Whatever comes back is the control your build actually has, and if nothing comes back, your build has no control and scanning is either always on or handled elsewhere.
The same approach finds the tile. Pull the notification shade fully down, open the edit or plus button that reveals the full tile list, and look for a scan tile. Drag it into the first row once and you never hunt for it again.
Bixby Vision has been leaving for years
For a stretch, Bixby Vision was the scanning route on Galaxy phones: a mode inside the Camera app with a barcode option sitting among image search and translation. It is not the route now. Samsung has been reducing and removing Bixby Vision across recent models, and on current devices it is either absent or reduced to a shell, with code reading handled by the camera's own detection and image work handed to Google Lens.
If a guide tells you to open Bixby Vision, the guide is old. That matters more than it sounds, because the instruction fails in a confusing way: the reader concludes the phone is broken rather than that a feature was retired.
Why the iPhone beside you read it and yours did not
Four reasons, in the order they actually occur.
The scan succeeded and the handoff did not. Samsung surfaces a detected code as a small bubble or a strip that needs a tap, and it can fade. If you were watching the poster rather than the screen, or a focus mode suppressed the notification, the decode happened and you missed the invitation. Ask what appeared on screen, not whether the page opened.
The code was too close to focus. Galaxy main and ultrawide cameras have a minimum focus distance around ten centimetres, and a small code held closer than that is out of focus, which no decoder recovers from. Back off to arm's length, and if the code is genuinely tiny, back off further and switch to the 2x or 3x lens so the code fills the frame at a distance the optics can resolve.
The code is marginal and one decoder is more patient. This is the honest answer more often than anybody likes. A code slightly undersized for the scan distance, or thickened by ink spread, or printed with weak contrast, reads on the more forgiving implementation and stalls on the other. The test that separates this from a software problem takes ten seconds: open a dedicated scanner app on the same Galaxy. If that reads the code, the symbol is usable and the camera path is the issue. If that fails too, the code itself is the problem.
The payload has no handler. A plain https URL opens anywhere. A custom app scheme, a geo link, or a payload for an app that is not installed can decode perfectly and go nowhere visible, so the phone looks broken while the decoder worked.
When the code is in a picture rather than in front of you
A screenshot, a saved poster, a code somebody sent in a chat: the camera cannot help, because there is nothing to point at.
Google Lens reads codes from images already on the phone, which on a Galaxy is usually the shortest route. Open the image in Gallery or Google Photos and use the Lens option. Scanning a code from a saved picture walks through the alternatives, and what Google Lens does and does not handle is worth knowing before you rely on it.
One habit is worth more than all of the above on a phone you use for work: decode the code without visiting the destination, and read the URL first. How to read a code without opening the link covers the apps that show you the string and stop.
The short version
Photo mode. Arm's length. Watch the screen for a bubble and tap it. If nothing appears, pull down Quick Settings and use the scan tile. If that fails, search Settings for QR and switch on whatever it offers. If it still fails, install a scanner app as a control, and if that also fails, the code is at fault rather than the phone.
None of this is a defect. Android's openness means several reasonable pieces of software can each claim the job, and Samsung ships more of them than most. Knowing which one you are using is the whole skill.
