This question already has an answer here:
My question is exactly the same as TTome! (Viewshed analysis plugin on QGIS keeps resulting in errors)
"I've been trying to test the Viewshed analysis plugin on QGIS 2.10, but it keeps giving back error messages. I've tried to reduce the radius area and have also reprojected both my DEM and my point shapefile to UTM, in order to avoid a possible memory error mentioned in another question regarding this plugin (that the using of geographic coordinates might cause a memory error). Still, I keep getting Python error messages when I try to run it. Does anyone know whats going on? Is this plugin "broken"?"