Cause
The connection above or below the connection definition point is branched into a T node, or a connection definition point is on two intersecting connections.
Solution
Possibility 1
Delete the target direction of the connection definition point in front of or behind the T node. Define separate connection definition points for the branching connections.
Possibility 2
Move one of the connections from the interface with the connection definition point.
Possibility 3
Move the connection definition point onto one of the connections so that the two connections can no longer interface with the connection definition point.
Refresh the connections and then start a new check run.