The embodiments herein relate to a method in a second CN node (205,407) for handling a failure in a communications network (200). The failure has caused communication between the second CN node (205, 407) and an old first CN node (203a) to become unavailable. The communication is associated with a session. When the failure has been detected, the second CN node transmits a session start request message to a new first CN node (203b, 405b, 410b). The session start request is a request to restore the session. The session start request message comprises a restoration flag indicating restoration of the session for a same service established before the failure and allowing a RAN node (201, 403) in the communications network (200) to accept the session start request message.