Blender 2.81 - gis add-on not working

The BlenderGIS-master add-on is able to import a basemap. Next should be the command “Get SRTM”, however that command results in an error (see attached screen shot).

The last command, “Get OSM” seems to work, but without the SRTM, the terrain is flat.

I am hoping someone has some idea what that error means. Thanks for any clues.