A user-agent is a string of text that a web browser or other client sends to a web server in an HTTP request header to identify itself. This string contains information about the browser type, operating system, and sometimes additional details like the browser version and the rendering engine used.

This is often requested as a security measure by servers, such as ones that host images, that can be passed via URL in the request body of the insert SKU file API.

This kind of authentication, however, is not currently supported by the VTEX APIs.

1 - Using either the Create or Update (write methods) SKU file API passing down an URL that has server-side user agent requirement to fetch data https://developers.vtex.com/docs/api-reference/catalog-api#post-/api/catalog/pvt/stockkeepingunit/-skuId-/file

2 - A 40x type response will be shown, either a generic 400 or a more specific 403 depending on the type of response implemented.

Either opt for the file upload va spreadsheet, form-data (using the APIs) or disable the user-agent requirements on the server-side.