I am having trouble running a script tool that I just created in Arc 10.1. The script runs fine in PythonWin, but when I create a script tool with it, the tool seems to not want to accept folders or geodatabases as its output workspace. I have the output parameter (argument) set as both an output and a workspace in the script tool, but it still keeps giving me an error that the "Dataset.....already exists"

I'm a new user, so I can't post a picture, but the error is 000725

Here is my script, if that helps out.

import arcpy
#allow for overwrites
arcpy.env.overwriteOutput = True

#set the workspace
inWorkspace = arcpy.GetParameterAsText (0)

#set the erase feature
eraseFeature = arcpy.GetParameterAsText (1)

#set the output workspace
outWorkspace = arcpy.GetParameterAsText (2)

#get a list of all the features in the workspace
arcpy.env.workspace = inWorkspace
featureClassList = arcpy.ListFeatureClasses()


    #loop through all of the features in the workspace
    for featureClass in featureClassList:

        #construct the output path
        outEraseFeature = outWorkspace + "\\erase_" + featureClass

        #perform erase
        arcpy.Erase_analysis(featureClass, eraseFeature, outEraseFeature)

        arcpy.AddMessage("Wrote clipped file " + outEraseFeature + ". ")
        print "Wrote clipped file " + outEraseFeature + ". "


    # Report if there was an error
    arcpy.AddError("Could not erase feature classes")
    print "Could not erase feature classes"
    print arcpy.GetMessages()
  • 3
    If it really does already exist you can try adding arcpy.env.overwriteOutput =True Dec 1, 2012 at 0:50

2 Answers 2


I found out that if I changed the direction of the output workspace from 'output' to 'input', then the script ran without an error.

  • thanks a lot - this hint finally solved my problem I have been working on for hours. Within my created python script an output folder should be specified to store a bunch of raster results. Setting it to Output created errors, now as I set it to Input it immediately worked.
    – the_chimp
    Mar 9, 2016 at 5:24

It is for your own protection. To not get that error, you need to enable this option:Overwrite Outputs.

Alternately, change your Output_Workspace to an input parameter rather than an output parameter.

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