Hello,
I am using Portal for ArcGIS 10.5.1, and I cannot print using the geoprocessing printing tools.
After configuring the GP printing tool, I could print my map from the web app builder application but not the Basemap.
But after some days, when it tried to print again, I was getting an error message.
As shown here below:

This is the error I get from the ArcGIS Manager logs:

My server is using a proxy.
Is there anyone who went through the same error?
Thanks,
Celine.