RuntimeError: ERROR 010093: Output raster format UNKNOWN is unsupported

Question

I have written a stand-alone Python script to perform an ExtractByMask operation on numerous raster files in ArcMap, that have a .bil extension format. However, when I try to save my output, I get the following runtime error:

enter image description here

Below is what my code looks like currently:

 #Import necessary system modules
 import arcpy,os
 from arcpy import env
 from arcpy.sa import *
 #Location where raster (.bil) files are located. 
 arcpy.env.workspace=r"D:\Mike_Daily_PRISM_PPT_from_2007_through2016\
 2007_Test"
 arcpy.CheckOutExtension('Spatial')
 #Location where output files should go after "for" loop has completed.
 outws=r"D:\Mike_Daily_PRISM_PPT_from_2007_through20162007円_Test\Output"
 #Location of the shapefile used to mask the PRISM raster(.bil) files
 mask=r"D:\Mike_Daily_PRISM_PPT_from_2007_through20162007円_Test\
 MissouriBound.shp"
 #Only search for files that have .bil extension. 
 rasterlist=arcpy.ListDatasets("*.bil","Raster")
 #Print the list of raster files that have a .bil extension
 print rasterlist
 #for i in rasterlist, perform an ExtractByMask function on each raster. 
 for i in rasterlist:
 outExtractByMask=ExtractByMask(i, mask)
 outname=os.path.join(outws, str(i))
 outExtractByMask.save(outname)

I believe the error has something to do with the format that it's trying to save the output format raster with. [Note: Actually, I would prefer to save the output in a TIFF format (.tif).] Can anyone confirm whether that is the issue with my code, and how I can then modify it to save the output with a .tif extension?

• PolyGeo: Please provide error messages as text rather than pictures so that they are available to future searches.

Answer 1

Yeah the error is coming up because you're trying to export each masked raster as a BIL. If exporting as a TIF is preferable anyway, it's an easy fix:

for i in rasterlist:
outExtractByMask=ExtractByMask(i, mask)
filename = str(i)[:-3] + 'tif'
outname=os.path.join(outws, filename)
outExtractByMask.save(outname)

Then it should run fine, exporting GeoTIFFs. Obviously you can change that to match whatever raster format (supported by Arc) you might want.