Hi Martin, This is Jerry in Esri Support Services. Are you polling an external ArcGIS for Server service, or something else? If you are accessing a secure ArcGIS Server Service, I think you will need to use the Esri Resource Proxy, Releases · Esri/resource-proxy · GitHub, rather than using the HTTP:BasicAuthentication transport -- this way the appropriate tokens are generated for ArcGIS Server. If it's a different kind of service, is it something you can create a mockup of in a publicly accessible environment so we can take a look? Thank you, Jerry Esri Support Services
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