What you are seeing
This fix restores the prefilled values to the form. You will decode the payload, check the link parameters, and test the form field by field, then repair the link or the form. Verify the fix by scanning the code and confirming every expected field arrives filled.
Likely causes
1.
Link parameters missing or mistyped — Quick test: decode the payload and compare the parameters with the form field names.
2.
Form does not accept prefill — Quick test: open the form with the parameters typed manually in the address bar.
3.
Redirect drops the parameters — Quick test: follow the redirect chain and watch the parameters.
4.
Field names changed — Quick test: compare the current field names with the parameters in the code.
5.
Values contain characters that break the link — Quick test: try a simple value with plain characters and compare.
Step-by-step fix
Step 1: Decode the payload and write down the exact link and parameters it carries.
Step 2: Compare the parameter names with the current form field names, letter by letter.
Step 3: Open the form with the parameters typed manually in the address bar. If they do not fill, the form is at fault.
Step 4: Follow the redirect chain and check that every hop preserves the parameters.
Step 5: Fix the parameter names, the redirect, or the form prefill setup, whichever is at fault.
Step 6: If the payload was wrong, regenerate the code from the corrected link.
Step 7: Retest by scanning the code on two phones and confirming every expected field arrives filled.
Putting this into practice
In practice, keep a record of the parameter names and the form fields they fill, and check it whenever the form changes. A form edit that renames a field silently breaks every code that prefills it. Record the before-and-after behaviour with the job file, so the fix is provable rather than anecdotal. When the same failure appears again, that record tells you whether the old fix held or a new cause appeared.
Common mistakes to avoid
- Regenerating the QR code when the form itself was never set up to accept prefilled values.
- 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 scans but the form is empty will be used.
- Changing the artwork and the placement at the same time, so you cannot tell which change fixed a code that scans but the form is empty.- Skipping the proof test because the change looked small, when small changes cause most repeat failures.
Quick checklist
- The parameter names match the current form field names
- Redirects preserve the parameters
- Scanning the code fills every expected field
- 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
Related tools and guides
- [survey QR code generator](/survey-qr-code-generator)
- [feedback QR code generator](/feedback-qr-code-generator)
- [QR payload inspector](/qr-payload-inspector)
- [QR redirect chain viewer](/qr-redirect-chain-viewer)
- [QR expiry checker](/qr-expiry-checker)
- [UTM builder](/utm-builder)
