Sync Merchant Center Error: https://support.simprosys.com/faq/how-to-synchronize-errors-from-google-merchant-center
Here is a quick link to install the app: https://apps.shopify.com/google-shopping-feed


Important Note:  Please, keep in mind, you should not waste time setting up the age group attribute for the products which are not in the “Apparel and Clothing” category.

On the diagnostics page in the Google Merchant Centre, you will find the list of products having multiple errors including “Missing Age Group”.

The error is highlighted in below-mentioned screenshot:

Here’s how you can solve this error:

• Click on “Filter products”. Select the option “Errors from Merchant Center” from the drop down menu.
• After synchronizing the errors, select ‘Missing Age Group Error” and Click on “Add Filter”.
• Apply respective additional filters to a particular group of products.
• Assign the right age group attribute to all the products having Missing Age Group error.
• If all the products are of the same age group, you can fix the error by selecting all the products at once.
• Once selected, choose the appropriate product age group from the drop down menu. 

• Click on “Apply in Bulk’.
• Now, click on the “Pending status” tab

• Open the product link in the Merchant center by clicking on the product’s merchant center link in the app.

In the Merchant center, it still displays “Missing Age Group” Error. 

• The merchant center will update the item status box within 3 minutes.
• Refresh the product page in the merchant center. You will see that the error is fixed.
• Now, go to Raw Feed Attribute of content API section, here you will see the age group attribute with the value assigned in the app.