000819: The tool is not assigned when running a Python toolbox in background geoprocessing

Last Published: April 25, 2020

Error Message

After installing the 64-bit Background Geoprocessing Upgrade, and running a Python toolbox in the background, the following error is shown in the results window and the tool fails to run:

"Error 000819: The tool is not assigned."


A third-party Python module that is referenced in the toolbox is not installed in the 64-bit Python folder for access by background geoprocessing. When the Python toolbox tool is run, 64-bit background geoprocessing cannot access the module in the 32-bit Python folder.

The toolbox appears to be valid with correct syntax because ArcGIS has access to the 32-bit modules, but does not check for the 64-bit modules.

Solution or Workaround

Install a 64-bit version of the third party module in the 64-bit Python folder.


Edit the Python toolbox's tools so they always run in the foreground by assigning the "self.canRunInBackground" line of code with False. For example:

class Tool(object):
def __init__(self):
"""Define the tool (tool name is the name of the class)."""
self.label = "Tool"
self.description = ""
self.canRunInBackground = False

Article ID:000011742

  • ArcMap

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