Cause
Possibility 1
A single-line connection definition point contains multi-line connection definitions that do not match the source or target. For example, the connection definition point has been moved or copied to a different connection, so the connection points for the new targets no longer match the old ones.
Possibility 2
The connection points for the multi-line functions at the targets have been changed, or the associated multi-line functions have been deleted.
Solution
Regarding option 1
Restore the associated multi-line functions or their connection points so that they match the multi-line connection definition for the connection definition point.
Regarding option 2
Delete the multi-line connection definition.
Then start a new check run.