I am trying to change the basemap of a WebMap portal item using the ArcGIS API for Python (1.9.1 version). It is indicated in this link arcgis.mapping.WebMap.basemap that we should use basemap property to set new basemap using Item object.
Upon setting a portal item as basemap using basemap property of WebMap object, I'm getting this error.
Here is my code where bm_item is an Item object. Is this an issue with the API version?