120132: Error in expression for <value>: Invalid left-hand assignment.

Description

While calculating values for the specified expression, a left-hand assignment error occurred.

Solution

A common example of a left-hand assignment error is when attempting to set a field that already exists. This causes a conflict in variable assignment. Verify that you are not attempting to calculate a new field with a field name that currently exists in the dataset. A common error is misuse of = and == in which = sets a value and == checks equality.