Issue uploading multiple images via commerce API

Hi,

I am using the commerce API to upload products from multiple suppliers but am running into an issue when trying to upload multiple images per product. As the API requires that images are sent individually we are uploading them 1 at a time but it is failing when we attempt to upload the 2nd image for each product and returns the following error message.

'Error:Invalid resource type: resource (closed)'

I have tried both manually closing the connection in between uploads and also adding a timeout of 5 seconds between the uploads but it is still failing. The application is in php and is using Guzzle 7 to create the connection. 

Has anyone else had this issue and how did you manage to resolve it?

Thanks