The Nintendo 3DS outer cameras are notoriously low-resolution by modern standards (0.3 megapixels). They struggle to scan blurry, pixelated, or low-contrast images. If you find a QR code on a forum or a video that is compressed or low quality, the 3DS will often fail to recognize it, giving a "Scan Failed" error.
In the 3DS homebrew community, a QR code serves as a direct link to the download URL of a (the 3DS game format). Instead of manually transferring files to an SD card, you scan the code to trigger an immediate download and installation. Where to Find High-Quality QR Codes gta chinatown wars 3ds qr code high quality
Note: To use these, you will need a high-quality image file. If you are searching for these on Google Images or Pinterest, search specifically for to avoid compression artifacts. In the 3DS homebrew community, a QR code