ERROR 000539: Invalid field <field name>

Last Published: July 19, 2023

Error Message

In some instances, running the Calculate Field tool to calculate the value of a field for a feature class or layer with a Python expression fails, and returns the following error message:

ERROR 000539: Invalid field <field name>
Image showing the error when the Calculate Field tool has failed.


This issue occurs if the field referenced in the Python expression does not exists or is misspelled. In this example, the ‘Number_of_Interns’ field is misspelled as 'Number_of_Intern' in the expression.

Image showing the misspelled field as Number_of_Intern.

The correct field name is ‘Number_of_Interns’ as displayed in the attribute table below.

Image showing the correct field name as shown in the attribute table.

Clicking the Verify Image showing the Verify button. button before running the expression does not check if the field exists or is misspelled. Therefore, it indicates the expression is valid without any error message.

Image showing the expression is valid after clicking the Verify button.

Solution or Workaround

Ensure or modify the Python expression in the Calculate Field pane to have the correct field name(s) before clicking Run. In this example, the expression references the correct field name of "Number_of_Interns", instead of the misspelled "Number_of_Intern".

Image showing the Calculate Field tool executes successfully after changing the misspelled field name to the correct field name.

Article ID:000023815

  • ArcGIS Pro 2 x

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