The problem may be related to passing crs='wktproj' to the rasterio.open call. Typically you don't need to pass anything here, and if you do it would be a proj4-style dict described at mapbox.github.io/rasterio/api/rasterio.crs.html . But "wktproj" is not a value that makes sense here.

Is your shapefile Lines or Polygons? It would need to be polygon.

Can't hurt to try to upgrade but I don't see anything obvious that would make me suspect a relevant bug was fixed between your version and now. The other thing I'd try is see if this same error surfaces with a different/unrelated raster and shapefile -- just to confirm nothing's screwy with the specific data sources you're using.

Is this really a duplicate? The linked question does nothing to describe what a Thiessen polygon is or how it relates to this question. Indeed, Thiessen polygons are only one possible solution to this question.

I wonder if you're hitting this bug hub.qgis.org/issues/13174 because the INPUT logged to screen is itself a temporary output. Are you on Windows? What version of the Processing plugin?

Does it run to completion if you uncheck the box "Keep resolution of output raster"? In the plugin source, GetGeoTransform is called only if that's checked: github.com/qgis/QGIS/blob/master/python/plugins/processing/a‌​lgs/…