Overview

Error code 21037 appears in Seller Central processing reports when a seller uploads a product listing file using an outdated or deprecated flat file template. Amazon periodically retires older versions of its inventory file templates and requires sellers to download and use the latest versions. If you encounter this error, it means your current file format is no longer accepted and you need to switch to the updated template.

Key Points / What Sellers Need to Know

• Deprecated templates trigger this error — Amazon retired several legacy flat file templates in 2021, including older versions of the Listing Loader, Book Loader, Price & Quantity file, and other inventory templates. Submitting any of these outdated files will return error 21037 in your processing report.

• Processing reports identify the issue — When you upload an inventory file through Seller Central or via API, Amazon generates a processing report. Error 21037 in that report specifically signals a template version mismatch rather than a data formatting problem.

• Updated templates are available in Seller Central — Amazon provides the current versions of all flat file templates in the "Add Products via Upload" section of Seller Central. Sellers must download fresh copies to ensure they are working with the accepted format.

• This error affects bulk listing workflows — Sellers who manage large catalogs through flat file uploads are most likely to encounter this error, particularly if they have been reusing the same template file for an extended period.

• Data migration is required — Simply renaming an old file will not resolve the issue. Sellers need to transfer their product data into the new template structure, as column headers and field requirements may have changed between versions.

What Causes Error 21037

Amazon periodically updates its flat file templates to accommodate new product attributes, comply with regulatory requirements, and improve data quality across the marketplace. When Amazon releases a new version of a template, the previous version enters a deprecation period before being fully retired. Once a template version is retired, any uploads using that format are rejected with error 21037 in the processing report. This change was implemented broadly in 2021 when Amazon overhauled several core inventory file templates simultaneously. Sellers who had been using saved copies of older templates — sometimes for years — suddenly found their uploads failing after the cutoff date.