I have been working with Arc Hydro Tools to perfom catchment analysis for a while now.
A few days ago, I encountered a new problem: The error warning 'Object reference not set to an instance of an object' after trying to compute drainage lines. In fact, all raster datasets produced by the Arc Hydro Tools before that step were without spatial reference. I tried Define Projection, but as soon as I click on the raster again it tells me the spatial reference is unknown. Even weirder is that after Project Raster and creating a completely new raster with an intact coordinate system, the same error would occur when trying to create drainage lines based on the projected rasters.
The next morning, everything worked fine again. Unfortunately, now I am getting the same error again and I'm running out of ideas. I cleaned my temporary files folder, set a spatial reference to the whole project, started a new project from scratch, restarted ArcMap and my Laptop various times..
Has anyone else run into this problem before? Or even found a solution? Any help would be greatly appreciated!