Configuration Error: deployment source '(projectname): war exploded' is not valid
This will happen when you remove an artifact that is already set in the configuration. You can see the artifact is red in the configuration:
To solve it, just removed the missing one and add another valid artifact.
Maybe you can try the following process.
1.Open Project Structure add an artifact (web application:exploded) from modules, select your module, add it:
2.Build Artifacts [(top menu) - build - build artifacts - build]
3.Edit Configurations - deployment add your artifacts