Each and every person walking on this earth possesses a distinct fingerprint that serves as their unique and unmistakable identity.

Products, too, have unique numerical identifiers generated for easier identification. In the e-commerce world, this is known as Global Trade Identification Number (or GTIN). These numerical barcodes are often found on a product beside or within the barcode itself. 

If you are a Google Merchant Center (GMC) or Shopify user, I am sure you are already quite familiar with this concept. One of the main reasons you need a GTIN is that it makes your paid or unpaid ad listings easier for customers to find. 

Products submitted to GMC without any unique product identifiers are difficult to identify. This leads to these products not being eligible for Shopping programs or features. 

Having any type of errors on Merchant Center is not good as they can eventually reduce the effectiveness and quality of your Ad campaigns. Even if you use E-commerce platforms like Shopify, you want to ensure you push your products to GMC without hassles. 

In this blog, we will discuss the common GTIN errors users experience in Google Merchant Center and how each one can be resolved. 

Common GTIN errors in Google Merchant Center & Solutions  

When assigning GTIN values to products, try to keep the following three points in mind: 

  1. If a product doesn’t have a GTIN, don’t submit one: If your product is unique to your store or your brand, it won’t have a GTIN–leave the GTIN field empty (skip to learn how)
  1. Use a valid GTIN: For all products and its variants, use the correct GTIN. Each product and variant (different sizes, colors, age group, etc.) have their own specific GTIN; ensure you enter the correct value GMC/E-commerce store. 
  1. Don’t submit GTINs in the restricted ranges: Certain ranges of GTINs are restricted and should not be used by manufacturers or retailers. These restricted ranges have the prefixes 02, 04, or 2, and they are reserved for internal use by certain organizations.

Now let’s explore the most common GTIN errors and how we can resolve them.

Missing GTIN/Limited performance due to missing value [gtin]

When you see an error that says “missing value [gtin]” or “Limited performance due to missing value [gtin],” it means Merchant Center suspects products submitted for a category have an existing GTIN, but the unique value has not been added for it.  

Ask your manufacturer to provide you with the appropriate GTIN(s). Then proceed to submit a value of ‘true’ for the identifier exists attribute (if GTIN exists). You can also extract GTIN from the barcodes provided on the products. 

different types of GTINs
Source: Gorilla 360 

Fixing It On Google Merchant Center

Step 1: Check the affected products 

Go to your Merchant Center Account -> Click on products in the navigation menu -> Click on diagnostics -> Click on item issues tab -> Download a list (.csv) of all affected products with missing value [gtin] issue (find the issue under the “issue” column).

Step 2: Submit valid GTIN values for products 

  • In the downloaded report, you can view all the products with missing GTIN values. 
  • Check that you have submitted the correct product data specifically for those products using the product ID (on GMC). Make sure each product has an accurate GTIN. 

Step 3: Resubmit product data 

  • After updating your product data, you can resubmit by either
    • Submitting through the Content API
    • Uploading a feed
    • Importing content from an e-commerce platform (Shopify, Amazon, Woocomerce, etc.) 
  • Next, return to your diagnostics page to check if the issue is fixed. It may take some time for the applied changes to reflect on the page. 

How To Fix Missing [gtin] on Shopify? 

Now, let’s talk about how to fix the missing GTIN error on Shopify. One option is to use the native Google Channel app that comes with Shopify. However, it’s important to note that this app has limited features and doesn’t send all product attributes to the Merchant Center.

So, what is the ideal solution? There is one, AdNabu. We help you fix the missing GTIN error by automatically scanning GTIN values from your Shopify store, checking if it is in the correct format, and then pushing those values to GMC. 

AdNabu helps you optimize your product data to meet Google’s requirements so your products don’t get rejected on GMC. 

We aim to help optimize product data as per Google’s standard so you can increase your visibility in search results. 

Here is a step-by-step process on how to add GTIN to a product on Shopify (AdNabu will automatically pick up GTIN values once you enter them and send it to Google Merchant Center): 

Step 1: Log in to your Shopify Store Admin Panel

The first step to adding a GTIN to your product is to log in to your Shopify store’s admin panel. This is where you manage all aspects of your online store.

Step 2: Go to Products

Once you’re logged in to your store’s admin panel, click on the “Products” option. This will take you to the page where you can view all the products in your store.

Step 3: Select the product to which you want to add GTIN to

Next, select the product to which you want to add the GTIN. Click on the product to open the product details page.

Step 4: Scroll down to the Inventory section

Scroll down to the “Inventory” section, which is located towards the bottom of the page. This is where you can add various details related to your product’s inventory, including the GTIN.

Step 5: In the Barcode field, enter the value of your GTIN

Finally, in the “Barcode” field, enter the value of your GTIN. Ensure that the value you enter is correct and matches the barcode on your product.

fixing gtin error on shopify

Adding GTIN to Product Variants

Start by going to the admin section of your Shopify store. Click the Products tab once you’re inside. Choosing the product to which GTIN should be added is the next step.

product variants gtin shopify

In the Variants section, continue to scroll down. Go ahead and click the Edit button there that you’ll see. Choose Edit barcodes from the dropdown menu that comes up.

You’re done once you click the Save button. It’s really that simple to add GTIN to your product variants. With this change, tracking and identifying your products will be even simpler.

That’s it, then! Your sales may significantly increase by quickly and easily adding GTINs to your product variants. Why not try it, then? Check out AdNabu for all your e-commerce needs if you’re looking for more ways to optimize your Shopify store.

Invalid GTIN 

invalid value gtin error
Source: WPromote

It is best to provide GTIN only if you are sure it is correct and sourced directly from your manufacturer. 

Entering incorrect GTIN will result in an invalid value [gtin] error. This happens when the GTIN value contains characters that aren’t numbers, has improper standard accepted formatting or invalid checksum. 

Pro Tip: GTIN can be found on the packaging of a product if it has a barcode. 

Fixing It On Google Merchant Center 

Step 1: Check which products are reflecting the invalid value

On Google Merchant Center, select products on the navigations and then diagnostics. Navigate to item issues and find the issue (in this case, invalid value [gtin]). 

Finally, click on the download option at the end of the row to get a list of all the products facing this issue. 

Step 2: Add Globally Valid GTIN (or remove errors)

Go to your product data and search using the ID for those products that were shown in your downloaded list (invalid gtin). Ensure each of these products is using an accurate GTIN. Remove any invalid values from the GTIN attribute field. 

(GTINs are often found to be invalid if there are too many or too few digits entered. GTINs are typically 8,10, 12, 13, or 14 digits. Also, the ‘check digit’ (last digit)  helps detect if you have mistyped a digit. Use this GS1 check digit calculator.)

Step 3: Resubmit product data 

After the first two steps, you can move ahead with resubmitting your product data through the following ways: 

  1. Content API 
  2. Import content from an E-commerce platform 
  3. Upload a feed

Step 4: Check your diagnostics page 

Go back to your diagnostics page to see if those issues are unlisted. Some changes may take time to reflect. 

How to fix an invalid GTIN on Shopify? 

AdNabu’s Google Shopping Feed app maps the GTIN from Shopify to Google Merchant Center automatically. AdNabu uses the barcode entered in Shopify for a product as the GTIN in Google Shopping. 

However, if the barcode is not correctly formatted or is too long or short, an error will occur in Google Merchant Center. To resolve the error, the barcode field in Shopify needs to be changed.

Read More: MPN – Google Shopping Feed Specification Guide

Duplicate value GTIN error

When two or more products are assigned the same GTIN values, you will incur a duplicate GTIN error. This could be because a product has been listed twice in your product data or you are using the same GTIN for two products. 

It also happens when merchants submit the same GTIN value for multipack products, which should actually be grouped together using the multipack attribute. 

While targeting the same language and country with multiple feeds, no duplication GTINs should be found across those feeds. To ensure Google can uniquely identify your products, you need to remove duplicate products, provide unique GTINs, and fix any errors in the multipack and condition attributes. 

How to fix it on Google Merchant Center?

Step 1: Check the affected products 

Go to the navigation menu in Google Merchant Center and select “Products.” Navigate to the “Diagnostics” section. Look for the specific issue, in this case, duplicate gtin in the “Item Issues” tab. Locate the row corresponding to the issue and at the end of the row, click on the “Download” option. By doing so, you will obtain a list containing all the products that are experiencing this particular issue.

Step 2: Key in unique values for each product 

In the downloaded report, you will see all the products with the issue of duplicate GTINs. Search your product data for those particular products using their IDs. Now submit correct GTIN values for each product and ensure you’ve submitted correct values for the multipack and condition attributes. 

Each variant will also have a unique GTIN, use the item group ID attributes for product variations. 

Step 3: Resubmit product data 

Once you have made the necessary updates to your product data, you can proceed to resubmit it using any of the following methods:

  1. Upload a feed
  2. Submit through the Content API
  3. Import content from an e-commerce platform

Step 4: Check your diagnostics page 

Go back to your diagnostics page to see if those issues are unlisted. Some changes may take time to reflect. 

How to fix it on Shopify? 

If you incur a ‘duplicate gtin’ error on GMC, you must key in the correct GTIN values on Shopify for each product. When you download the list of the products that are causing this issue, key in the correct value for them on Shopify. 

GTIN Not Registered 

If your GTIN has not been registered yet, don’t worry, allow us to walk you through the very simple process to generate GTIN for your products. 

How to create GTIN?

Step 1: Apply for GTIN 

First, visit GS1 US website.

Step 2: Selection Plan and Information Input 

On visiting the website, you will notice you have two options; you can opt for either a single GTIN option, which will allow you to generate a few barcodes for $30 with no renewal fee. The other option you can choose is the ‘Company Prefix’ Option. This option allows companies who need 10 or more GTINs to generate GTINs on cost per prefix, which allows you to pay flexibly as per your requirements (10, 100, etc.)

Choosing either option will take you to a screen where you can put in the name of your brand, your company, and the number of UPCs that your company requires. Followed by this, you will be asked to put in your contact information and payment information. 

Step 3: Receive your GTIN  

You will soon receive an email from GS1 US with the GTIN or the Company Prefix. You will also receive the login information for GS1 US Data Hub. Data Hub will help you create JPEGs of UPC Barcodes based on the information sent by GS1. 

You can also use a specializing solution provider that can generate Barcodes for you. GS1 recommends a couple of solution providers. They are listed below. 

  1. Syndigo:  It will help you create a continual flow of content and data in between brands, distributors, retailers, and their customers.
  2. Comarch: Available in 40+ countries, Comarch is yet another global provider of B2B EDI networks. 
  3. AccuGraphiX: A provider that has been in existence for over 37 years. They print and mail users the barcodes, labels, etc, within a day. 

GTIN Not Assigned

If you manufacture your own products, there is a high chance you have not assigned them any GTINs. These products fall under the category of custom products (e.g., handcrafted goods, custom-printed apparel, etc.). In that case, you can leave the GTIN field empty (or if you want, you can purchase one, too, this is optional). 

On Google Merchant Center: 

To leave the GTIN field empty, you need to add an attribute and change the settings.

Step 1: Change the feed rules (add attribute)

select the feed you want to change rules of

Click on products in the navigation menu, then click on the feed you want to change the rules of and navigate to the settings tab. Click on the feed rules, then click the plus sign button. 

feed rules

Type in ‘identifier’ into the search field, and you will see the option of ‘identifier exists’ in green, click on that. 

Step 2: Change the value of the attribute to ‘false’

By default, once you click on the ‘identifier exists’ option, you will be redirected to a page, in which on the right-hand side, you will see text reading ‘true’. 

On the left hand side you will see text reading, ‘data sources’, click on add data source. Click on ‘set to’, and a dialogue box will pop up. Type in ‘no’, then a second dialogue box will appear, in the ‘add value’ section click on ‘no’.

data sources

The value has been set to ‘no’

value has been set to no

Step 3: Save feed rules setting

Proceed to click on ‘Ok’ to save your settings. You will be redirected to the previous screen, and see the value as ‘false’ appearing on the right-hand side. 

Finally, click on ‘save as draft’, it will take you back to the main screen, where you need to click on ‘Apply’. 

Et voila!

On Shopify: 

To leave it empty on Shopify, we recommend using AdNabu’s product feed app to make it easier for you. Doing it via the Google channel app is risky as the app does not correctly send the GTIN information to GMC and is known to cause errors.

If the GTIN field is left empty, our app will send the GTIN value as ‘null’, so your products are not disapproved by Google Merchant Center because of this issue. 

However, some products are widely manufactured, and Google is aware that those products have a GTIN–for those, you will have to add their GTIN. 

Frequently Asked Questions (FAQs)

  • How Does The Google Channel App On Shopify Add To GTIN Errors?

The Channel app is a free app with limited features, which may result in incomplete product information being sent to the merchant center. Even if the product details include the Barcode/GTIN, this information may not be sent to the merchant center. Additionally, if the Channel app is connected to the merchant center alongside another feed app on Shopify, the Channel app’s updates may cause errors and confusion in the merchant center.

  • How Does AdNabu Fix GTIN errors?

AdNabu pushes all the fields that are required to have a well-optimized shopping feed, including GTIN. We also check the GTIN format before sending it to GMC so users know beforehand if there are any errors to avoid products being disapproved. 

  • Is it compulsory to have a GTIN? 

A GTIN is not compulsory for all products, but it is certainly a requirement for many retailers as a way to track and manage their inventories. Hence, it becomes important to check the specific requirements of each and every retailer or marketplace where they plan to sell their products.

  • Can a GTIN be reused for a different product?

No, a GTIN cannot be reused for a different product. Each GTIN is unique to a specific product and is used to identify and track it throughout the supply chain. Trying to reuse a GTIN for a different product can cause confusion and errors in inventory management and tracking.

  • Can a GTIN be used internationally?

Absolutely! GTIN is an internationally recognized product identifier, so you can use it to label and track your goods across international borders. Just make sure to follow the specific guidelines and standards of the country you’re operating in.

  • What is the relationship between a GTIN and a barcode?

Well, a GTIN is a unique identifier for a product, while a barcode is a graphical representation of that identifier that can be scanned by a barcode reader. So basically, a barcode is just a visual way of displaying the GTIN.

  • Are GTINs required for all products?

A GTIN is required for all products that have been listed on your product page. Any product changes (such as a variation) will also require a GTIN to be generated. 

  • How can I verify the accuracy of a GTIN?

You can verify the code you received from GS1 US by cross-referencing the data. You can also verify the validity of your GTIN here (the official website of GS1 US to verify your GTIN from their registry.) 

  • What is the difference between a GTIN-12, GTIN-13, GTIN-14, and GTIN-8? 

A GTIN-8 is an 8-digit code similar to GTIN-13 (a 13-digit code), used outside of North America. On the other hand, GTIN-12 is used predominantly in North America. GTIN-14 is a code that is used at various packaging levels to identify different products. 

  • Can a product have multiple GTINs?

Ideally, a product should only have one GTIN allocated to it. However, there may be a possibility that different brands may allocate different GTINs for similar products. 


Use this information to resolve any GTIN issues you may encounter on Google Merchant Center or Shopify. The GTIN issue is easy to resolve and not a cause for concern in any way. 

If you have any additional queries or issues, you can always reach out to our support team: support@adnabu.com