ID:251016 Cannot save incorrect assignment -- error: <text>

CAUSE: You saved assignment edits in the Assignment Editor, but one of the assignments did not pass legality checking. The Quartus Prime software cannot save incorrect assignments. Assignments with errors or potential errors appear in bright red by default in the Assignment Editor.

ACTION: Edit the assignments so that all required fields are complete and contain legal settings. For more information about the error, click the + icon to expand this message in the Messages.