diff --git a/src/vnet/session/session_types.h b/src/vnet/session/session_types.h
index 7cfa671..95a88c5 100644
--- a/src/vnet/session/session_types.h
+++ b/src/vnet/session/session_types.h
@@ -505,7 +505,8 @@
   _ (NOEXTCFG, "no extended transport config")                                \
   _ (NOCRYPTOENG, "no crypto engine")                                         \
   _ (NOCRYPTOCKP, "cert key pair not found ")                                 \
-  _ (LOCAL_CONNECT, "could not connect with local scope")
+  _ (LOCAL_CONNECT, "could not connect with local scope")                     \
+  _ (TRANSPORT_NO_REG, "transport was not registered")
 
 typedef enum session_error_p_
 {
diff --git a/src/vnet/session/transport.c b/src/vnet/session/transport.c
index 54ce917..192a201 100644
--- a/src/vnet/session/transport.c
+++ b/src/vnet/session/transport.c
@@ -314,6 +314,8 @@
 int
 transport_connect (transport_proto_t tp, transport_endpoint_cfg_t * tep)
 {
+  if (PREDICT_FALSE (!tp_vfts[tp].connect))
+    return SESSION_E_TRANSPORT_NO_REG;
   return tp_vfts[tp].connect (tep);
 }
 
@@ -343,6 +345,8 @@
 transport_start_listen (transport_proto_t tp, u32 session_index,
 			transport_endpoint_cfg_t *tep)
 {
+  if (PREDICT_FALSE (!tp_vfts[tp].start_listen))
+    return SESSION_E_TRANSPORT_NO_REG;
   return tp_vfts[tp].start_listen (session_index, tep);
 }