I wonder if anyone could help me out, i am kind of a beginner at QGIS. I´ve built a DEM for a project that i am developing than i´ve made the slope raster with the terrain analysis,it seemed that worked everything fine. But for further development of my work i ll need to vectorize some slope classes,but unfortunately every time i go Raster>Conversion>Polygonize; i get a error message (image with the error attached to this question). I thought that could be something wrong with the DEM that i ve produced.Just to check it i downloaded a DEM from ASTER DEM and i tried to do same with these and the same error occurs! Could be a software bug? Or am i doing something wrong? Or there is another way of doing this?