ERROR999999, [Failed to open raster dataset], and [Client tried to access password-protected page without proper authorization]

Error Message

The Export Training Data for Deep Learning tool fails when the image service used for input is on a different federated server from the raster analytic server. An error similar to the following and shown in the image below is returned.

ERROR 999999: [Failed to open raster dataset], and [Client tried to access password-protected page without proper authorization]

To improve performance, cluster deployments are recommended when using ArcGIS Deep Learning Studio.

Cause

There is an known issue with the portal failing to access input imagery with the expected token.

Solution or Workaround

The workaround is to temporarily share the item to be public for exporting image chips to complete. 

1. Share the input imagery layer to Everyone (public) on the portal. 
2. In ArcGIS Deep Learning Studio, collect the necessary training samples and select the Manage image chips sub-step.
3. Export the image chips from the input image service.
4. Once complete, change the sharing level for the input imagery layer to the desired level.