The 'Calculate Field' tool fails to execute and returns the error message, "000310: The Field name must not start with a number."

Workaround

1. Ensure the original field Shape_Area is selected as the input, instead of the 0.Shape_Area field.
2. After every selection in the 'Calculate Field' tool, select and re-select Shape_Area.
3. After validating the expression, re-select Shape_Area, and close the tool.
4. After the model is validated, re-open the tool, and re-select the Shape_Area field.
5. Close the tool, and the model runs successfully.

Steps to Reproduce