The Square Catalog API does not support uploading images by sending the image contents directly. Instead, you need to use the CreateCatalogImage endpoint to upload an image file from a server. The image file should be stored on a server and the server path to the image file should be specified in the CreateCatalogImage request. The API does not support directly embedding image data in the request.
In your case, you’re getting a “Resource not found” error because the API is expecting a server path to an image file in the request, but it’s not finding one.
To resolve this, you would need to first save the image file to a server, and then provide the server path to that image file in your CreateCatalogImage API request.
This answer was reviewed by @Bryan-Square.