WMS attribute popups fail to render in Map Viewer if the header X-Frame-Options: SAMEORIGIN is returned by the hosting server

Description

Map Viewer and Map Viewer Classic do not render feature attributes in a popup for certain OGC WMS services. The popup displays, but no attribute information is contained, as shown in the next image.

The equivalent popups display correctly in ArcGIS Pro.

Cause

Map Viewer displays popup attributes in an iframe within the popup for security reasons. If the WMS is configured to return the header.

X-Frame-Options: SAMEORIGIN

To the GetFeatureInfo request generated by ArcGIS Online for the popup, the response (attributes) is blocked from displaying in an iframe unless the request is coming from the same origin as the server.

Solution or Workaround

The solution is to have this response header removed at the hosting server end, or to display the attribute popups in ArcGIS Pro instead.