Your phone will typically not use the flash when scanning a QR code,and so a brightly lit area is crucial for a successful scan. Make sure your windows are open or lights are turned on for the camera to detect the code. Make sure your shadow is not obstructing the light from reaching the code.
Make sure your barcode or QR code is positioned within the viewfinder of your scanning app. If the code is not positioned correctly, your code will not be detected.
Patterns on a tablecloth, rug or wall in the background can sometimes confuse your camera’s auto-focus feature and prevent the code from scanning. If your product is set against a pattered background, try moving it to a plain background and scanning again.
Your phone’s camera may have trouble scanning the code if it’s tilted at an angle. Make sure it’s level with the surface that the code is printed on.
If you’re holding your phone too close or too far away, it won’t scan the code. Try holding your phone about a foot away and slowly moving it towards the QR code, until the code is successfully scanned.
Your phone’s lens can pick up a lot of dust and smudges that can affect image clarity, so give it a wipe with a soft cloth to clean it off, and try scanning again.