Message type: E = Error
Message class: S~ - Repository API Business Navigator
Message number: 101
Message text: On node & (typ &) exists a loop
It exits a line, where the predecessor node is also the successor node.
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
You have to correct the line definition in your model.
Error message extract from SAP system. Copyright SAP SE.