Fixing GTIN/Identifier Errors

GTINs (Global Trade Item Numbers) are unique product identifiers like UPCs and EANs. Incorrect or missing GTINs are a frequent cause of product disapprovals.

Understanding GTINs

GTIN Types

Type	Length	Region	Example
UPC-A	12 digits	North America	012345678905
EAN-13	13 digits	International	4006381333931
ISBN	13 digits	Books	9780306406157
GTIN-8	8 digits	Small products	12345670
GTIN-14	14 digits	Cases/pallets	10012345678902

When GTIN is Required

Scenario	GTIN Required
New branded products	Yes
Products with barcodes	Yes
Custom/handmade	No
Vintage/antique	No
Private label (no barcode)	No

Common GTIN Errors

Invalid Format

Error: “GTIN format invalid”

Causes:

Wrong number of digits
Non-numeric characters
Leading zeros removed

Fix: Verify GTIN has correct length including leading zeros.

Invalid Check Digit

Error: “GTIN check digit invalid”

Cause: Last digit doesn’t match calculation.

Fix:

Verify GTIN from original source
Use GTIN validator
Correct the number

GTIN Mismatch

Error: “GTIN doesn’t match product”

Cause: GTIN belongs to a different product.

Fix:

Verify GTIN matches exact product
Check variant-specific GTINs
Get correct GTIN from manufacturer

Validating GTINs

Manual Check

Count digits (8, 12, 13, or 14)
Ensure all numeric
Verify check digit

Check Digit Calculation

For GTIN-13:

Sum odd positions × 1
Sum even positions × 3
Total sum mod 10
Check digit = 10 - result (or 0 if result is 0)

Or use: GS1 Check Digit Calculator

Lookup Tools

Verify GTIN matches product:

Fixing GTIN Errors

Step 1: Find Correct GTIN

Source	How
Product packaging	Check barcode
Manufacturer data	Contact supplier
Purchase order	Check original documentation
GS1 database	If registered

Step 2: Update in Feedy McFeed Feed

Individual product:

Go to Products > select product
Enter correct GTIN
Save

Bulk update:

Export products with GTIN errors
Add/correct GTINs in spreadsheet
Import updated file

Step 3: Verify and Regenerate

Check validation passes
Regenerate feed
Monitor for approval

When You Don’t Have GTINs

Use identifier_exists: false

For products genuinely without identifiers:

Go to Products > select product
Enable “No identifier exists”
Leave GTIN blank
Save

Valid reasons:

Handmade/artisan products
Custom-made items
Vintage/antique
One-of-a-kind items

Invalid reasons:

Don’t know the GTIN
Don’t want to look it up
Competitor products

Provide Brand + MPN

Alternative to GTIN:

Set brand (manufacturer name)
Set MPN (manufacturer part number)
Both are required together

brand: Samsung
mpn: UN65TU7000FXZA
gtin: (blank)

GTIN for Variants

Each variant typically has a unique GTIN:

Product	Variant	GTIN
T-Shirt	Small/Red	012345678901
T-Shirt	Medium/Red	012345678902
T-Shirt	Large/Red	012345678903
T-Shirt	Small/Blue	012345678904

Setting Variant GTINs

Go to Products > select product
Click Variants tab
Enter GTIN for each variant
Save

Getting GTINs

Purchasing from GS1

If you manufacture products:

Join GS1
Get company prefix
Assign GTINs to products
Register in GS1 database

From Suppliers

If you resell:

Request GTINs from manufacturer
Check wholesale/B2B portals
Use product data feeds from suppliers

Troubleshooting

GTIN validation passes but still disapproved

Possible causes:

GTIN registered to different product
GTIN in incorrect GS1 database
Product details don’t match GTIN registration

Solution: Verify GTIN matches exact product through lookup tools.

Different GTIN in different systems

Issue: Shopify, supplier, and feed have different GTINs.

Solution:

Verify physical product barcode
Use that GTIN in all systems
Report errors to data sources

Valid GTIN flagged as invalid