001489: Cannot project a feature class that participates in more advanced capabilities (such as topology and geometric network).

Description

When a feature class in a feature dataset under a geodatabase participates in a geometric network, topology, terrain, or other advanced data structures within that feature dataset, then its spatial reference cannot be changed through the Project tool if you want to send the output to a geodatabase.

Solution

Set the output to be a shapefile, or project the entire feature dataset.

You can also use the Copy Features tool by setting the output coordinate environment to the desired spatial reference.