Cannot load data from data source

Error Message

Using the Add Field tool located in ArcToolbox > Data Management Tools > Fields to add a field returns the following error:

"Could not load data from the data source. If you can correct the problem press the refresh button to reload data.."

Cause

This is a known issue when having the attribute table open in the background.

Solution or Workaround

• Close the table before adding a field.
• Once the error message appears, click OK. The tool will finish running, and the attribute table will go blank. Close the table and reopen it, and the new field should appear.