How to migrate web maps using the beta version of the Dark Canvas Basemap to the production services
Download this script and run it twice from a command line as indicated below to migrate both the reference and base layers of the basemap.
python updateWebmapServices.py https://www.arcgis.com [ADMIN-USERNAME] [PASSWORD] [SEARCH-QUERY] http://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/World_Dark_Gray_Reference_Beta/MapServer http://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Reference/MapServer
python updateWebmapServices.py https://www.arcgis.com [ADMIN-USERNAME] [PASSWORD] [SEARCH-QUERY] http://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/World_Dark_Gray_Base_Beta/MapServer http://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Base/MapServer