Confirm the application pool being used in IIS:
- Click on "Advanced Settings..." from the "Actions Pane" or right-click the site and choose "Manage Application | Advanced Settings...":
The dialog will list the Application Pool in use:
- Select "Application Pools". Locate the relevant application pool then select "Start" from the "Actions" pane, or right-click the application pool and select "Start":
Test the web portal to confirm the application pool is now running correctly.