Hello,
Could you please provide more details about what you mean by changing the workspace?
Did you create a new workspace and then open the project from another workspace? Or did you copy the project directory to the new workspace and then load existing project?
Did you use the import existing project wizard?
Did you try a Clean Build command first? It might be trying to perform an incremental build from the previous workspace.
Please check the path variable is set correctly for the project:

Best Regards,
Mike