Assign nulls to a field in ArcGIS Pro

Last Published: May 10, 2022


In ArcGIS Pro, an attribute table sometimes contains multiple fields with null values and populated with a space by default. In some instances, some tools or functions do not execute if the field is blank as shown in the image below.

The attribute table displayed the empty space for a field named Source.

This article describes the workflow to assign nulls to a blank field in ArcGIS Pro.


This workflow only applies for data stored in a geodatabase and when the field is nullable. Refer to ArcGIS Pro: Export data or ArcGIS Pro: Modify field properties for more information.
  1. Open the ArcGIS Pro project.
  2. In the Contents pane, right-click the feature layer and select Attribute Table.
  3. Right-click the field header and select Calculate Field to open the Calculate Field window.
  4. In the Calculate Field window, the Input Table and Field Name (Existing or New) parameters are automatically selected.
  5. For Expression Type, select Python 3.
  6. Copy the following expression and paste it into the Expression box.
  1. Click the Verify The Verify icon. icon to validate the expression.
  2. Click Apply.

The Calculate Field window with a message, 'This tool modifies the Input Table' returned.

The image below shows the Source field assigned with nulls in ArcGIS Pro.

The attribute table displayed nulls is assigned to the Source field in ArcGIS Pro.

Article ID:000027567

  • ArcGIS Pro 2 8 x
  • ArcGIS Pro 2 7 x
  • ArcGIS Pro 2 x

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