003402: Cannot rename the default project toolbox.
Description
The default project toolbox is an integral part of an ArcGIS Pro project, and its name cannot be changed.
Solution
If you need a toolbox with a specific name, create a new toolbox.
The default project toolbox is an integral part of an ArcGIS Pro project, and its name cannot be changed.
If you need a toolbox with a specific name, create a new toolbox.