Cause

In the project-specific settings, you have defined a mandatory property <y> for a segment definition <x>. But in the pre-planning, a value was not stored at the defined mandatory property for this segment definition.

Solution

1. Locate the output segment definition in question in the project using the Go to (graphic) or Synchronize selection functions offered by the popup menu of the Message management dialog.
2. Open the Properties <...> dialog of the segment definition, and bring to the front the corresponding tab that contains the properties.
3. Assign a value to the mandatory property output in the Message management dialog for the segment definition, and close the Properties <...> dialog with [OK].
4. Then start a new check run.