In general, techniques are described for handling errors in subscriber session management within mobile networks. A downstream mobile gateway comprising a forwarding unit and a service unit may implement the techniques. The forwarding unit receives a packet that includes a destination address for a subscriber and a tunnel endpoint identifier (TEID). The service unit determines whether the TEID is associated with one of a number of subscriber records that store session data for current sessions associated with subscriber devices to communicate with the mobile network. In response to determining that the TEID is not associated with one of the subscriber records, the service unit generates a message that includes the TEID and the destination address and indicates that the downstream mobile gateway has determined that the TEID is not associated with one of the subscriber records. The forwarding unit then sends the message to the upstream mobile gateway.