Print QR labels

Create a revocable QR identity for each physical unit, then download one label or generate a printable sheet for a pool, selection, or filtered unit list.

What you'll accomplish

• Print QR codes that open the correct unit passport without putting the serial in the URL.
• Add the serial, SKU, product title, shop name, or a Code 128 warehouse barcode.
• Verify alignment and scan reliability before printing a production run.

Requirements

• The Warranty or Ops plan.
• A connected Shopify store with the app proxy permission active.
• Real units. Demo preview units are never issued QR identities or included in batches.

If Settings → Public Lookup is off, labels can still be generated. Buyer scans show a neutral unavailable page until lookup is enabled.

Create a label batch

1. Open Serials → Labels.
2. Select Create labels.
3. Choose the current unit filter, selected units, or one pool.
4. Choose Avery 5160, Avery L7160, A4 large, or a custom A4/Letter grid.
5. Select the optional label contents. QR is always included; Code 128 and serial text are on by default.
6. Check the server-rendered preview, then select Start label batch.
7. Keep the Labels page open to watch progress, or return later. Download appears when the batch completes.

Large batches are split at 500 labels per PDF. If a batch has more than one PDF, the download is a ZIP containing every numbered part and a checksum manifest. Download links expire after 24 hours, and generated files are retained for 14 days.

Download one unit label

Open a unit passport and find QR identity. Select Prepare QR downloads, then download PNG, SVG, or a single-label PDF. Preparing downloads is safe to repeat and does not replace an existing QR.

Use Regenerate QR only for a lost, leaked, or incorrect label. Regeneration immediately revokes the previous identity, so every older printed QR for that unit returns a neutral not-found result.

Print reliably

1. Print the PDF at 100% or Actual size. Do not use Fit, Shrink, or Scale to page.
2. Turn browser or PDF-viewer headers and footers off.
3. Print one test sheet on plain paper and hold it behind the label stock to verify every edge.
4. Scan QRs from the first, middle, and last rows with a phone camera.
5. If Code 128 is enabled, scan the same samples with the warehouse wedge scanner in Serials → Scan.

Serial Trail enforces an 18 mm minimum QR width. It rejects a Code 128 barcode before generation when the serial would make its bars too dense for the selected cell.

What success looks like

• Each QR opens the intended unit on the store's /apps/serial-check/q/… path.
• A valid unit shows the genuine state; a voided unit shows not valid.
• Code 128 sends the serial to the scan hub without manual typing.
• Label edges remain aligned from the first row through the last row at 100% scale.

Troubleshooting

Scans show “Product passport unavailable”

Likely cause: Public Lookup is disabled, the store plan no longer includes QR labels, or the app proxy permission is missing.

Fix: Enable Settings → Public Lookup, confirm the Warranty or Ops plan is active, and reconnect Shopify if Serial Trail requests the app proxy permission. Scan the label again in a private browser window.

The sheet drifts out of alignment

Likely cause: The viewer scaled the PDF or added headers and footers.

Fix: Select Actual size or 100%, turn headers and footers off, and confirm the paper size matches the preset. Use a custom grid only after measuring the stock in millimetres.

Code 128 does not fit

Likely cause: The serial is too long for the selected label width.

Fix: Choose A4 large, reduce optional text, or turn Code 128 off. The QR remains available.

The download is no longer available

Likely cause: The signed link expired after 24 hours or the artifact passed its 14-day retention window.

Fix: Refresh Serials → Labels for a new signed link. If the artifact was pruned, start a new batch; existing unit QR identities remain unchanged.