What you are seeing
The printed code is missing one of its three large corner squares, or one corner is so damaged that the scanner cannot recognise it. Without all three finder patterns, the scanner cannot locate or orient the symbol, so the code fails outright. The cause is usually physical: a logo, a sticker, a fold, a trim, or a print fault that removes a corner. The fix is to restore all three corners and to protect them from anything that covers or cuts them.
Likely causes
1.
Logo or graphic covering a corner — A logo, a badge, or a decorative element placed over a corner hides the finder pattern. Test: compare the proof corners with the digital file.
2.
Trim cutting off a corner — A code placed too close to the trim edge can lose a corner when the sheet is cut. Test: check the margin at the trim side on several copies.
3.
Fold, crease, or damage across a corner — A fold line, a scratch, or a scuff that crosses a corner can destroy the pattern. Test: inspect the proof corners for folds or damage.
4.
Print fault in one corner — A clogged nozzle, a band, or a faded area can wipe out a corner. Test: check whether the same corner fails on every copy.
5.
Sticker or label overlapping the code — A sticker, a price label, or a seal placed over the code can cover a corner. Test: look for any overlapping label on the finished item.
Step-by-step fix
1. Inspect all three corners of the proof and note which one is missing or damaged.
2. Compare the proof corners with the digital file.
3. Remove anything covering the corner: a logo, a sticker, a fold, or a trim overlap.
4. Move the code away from the trim edge if trimming cut the corner.
5. Fix the print fault if the same corner fails on every copy.
6. Reprint one proof and confirm all three corners are complete before approving the run.
Putting this into practice
In practice, the finder patterns are sacred: nothing may cover, cut, or damage them. Keep logos centred and small, keep stickers and labels clear of the corners, and keep the code away from folds and trim edges. A corner check on every proof takes seconds and catches this failure before it reaches the run. Keep a short note of what you tested, what failed, and what you changed, so the next person starts from evidence rather than guesswork. A fix that is written down survives staff changes and reprints; a fix that lives only in memory gets repeated.
Common mistakes to avoid
- Placing a logo over a corner finder pattern and discovering the code cannot be found by any scanner.
- Reprinting the full run before a single proof passes, which turns one failure into many.
- Testing on one phone in ideal conditions instead of two phones in the real conditions where a code that prints with a missing finder pattern will be used.
- Changing the artwork and the placement at the same time, so you cannot tell which change fixed a code that prints with a missing finder pattern.- Skipping the proof test because the change looked small, when small changes cause most repeat failures.
Quick checklist
- All three finder patterns are complete and match the file
- No logo, sticker, fold, or trim touches a corner
- The proof scans on two phones
- The corrected proof passes on two phones in the real conditions
- The fix is recorded in the job file so the next reprint starts from a proven setup
- Every printed copy is checked against the approved proof
- The proof is retested after any later change to the link, design, or placement
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- [QR contrast checker](/qr-contrast-checker)
- [QR print proof checklist](/qr-print-proof-checklist)
- [QR DPI calculator](/qr-dpi-calculator)
- [QR quiet zone calculator](/qr-quiet-zone-calculator)
- [printed QR tester](/printed-qr-tester)
- [QR size calculator](/qr-size-calculator)
