3738538 - Error in CatalogUploadRequest: "Transmission error while connecting to target system for the customer"

When running the ARBCIG_BUYER_CATALOG_EXPORT program in the ERP, to send the Catalogs to the Managed Gateway for Spend Management. The Transaction in question is failing with the following exception:

• Transmission error while connecting to target system for the customer ANXXXXXX with HTTP ResponseCode:413 and FAILED with ..
• Suggested Action : Connectivity to target system failed. Common HTTP error responses and suggestive actions. 500 (Internal Server Error) -> Check in the target system for exact nature of request failure.400-4XX (Authentication Issue) -> check target system provided valid authentication details.ErrorCode:CIG-PLT-00645.

catalog upload request, http 413, request entity too large, CIG-PLT-00645, managed gateway, ismg, ariba network, document size error, status code 499, catalog size limit, 10 mb, cxml catalog, connectivity to target system failed, reprocess fails, buying and invoicing , KBA , BNS-ARI-CI-BUY-CATEX , Managed Gateway for Procurement Catalog Export , SBN-AN-CAT-PUB , Catalog Publishing , BNS-ARI-CM-ADM-TSK , Catalog Scheduled Tasks , Problem