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

Receive notifications and find solutions for new or common issues

Get summarized answers and video solutions from our new AI chatbot.

Download the Esri Support App

Related Information

Discover more on this topic

Get help from ArcGIS experts

Contact technical support

Download the Esri Support App

Go to download options