Always when working with raster layers errors happen. Can´t warp (reproject) layer, or extract contour, for example. I have unistall Qgis and install back several times in different ways, but didn´t work. I work with MacBook. This is an example of one of the errors:
The following layers were not correctly generated.
You can check the 'Log Messages Panel' in QGIS main window to find more information about the execution of the algorithm.