In ArcGIS Viewer for Flex 3.7, the default basemap must be both a cached map service and in the Web Mercator Auxiliary Sphere projection or switching to a Portal for ArcGIS basemap included with Flex Viewer displays a blank, white background.
Last Published: August 6, 2015ArcGIS Viewer for Flex
Bug ID Number
February 13, 2015
June 11, 2020
ArcGIS Viewer for Flex
Will Not Be Addressed
The development team has considered the issue or request and concluded it will not be addressed. The issue's Additional Information section may contain further explanation.
No more changes are being implemented
Use one of the Esri basemaps included with the application as the default basemap.