diff --git a/proxy/socks5/server.go b/proxy/socks5/server.go
index d8eaa16..3dd10ec 100644
--- a/proxy/socks5/server.go
+++ b/proxy/socks5/server.go
@@ -145,6 +145,7 @@ func (s *Socks5) serveSession(session *Session) {
 	dstC, dialer, writeTo, err := s.proxy.DialUDP("udp", session.srcPC.tgtAddr.String())
 	if err != nil {
 		log.F("[socks5u] remote dial error: %v", err)
+		nm.Delete(session.key)
 		return
 	}
 	dstPC := NewPktConn(dstC, writeTo, nil, false, nil)
diff --git a/proxy/ss/server.go b/proxy/ss/server.go
index 79f80eb..a9fe535 100644
--- a/proxy/ss/server.go
+++ b/proxy/ss/server.go
@@ -132,6 +132,7 @@ func (s *SS) serveSession(session *Session) {
 	dstC, dialer, writeTo, err := s.proxy.DialUDP("udp", session.srcPC.tgtAddr.String())
 	if err != nil {
 		log.F("[ssu] remote dial error: %v", err)
+		nm.Delete(session.key)
 		return
 	}
 	dstPC := NewPktConn(dstC, writeTo, nil, false)
diff --git a/proxy/tproxy/server.go b/proxy/tproxy/server.go
index 3982c37..4adcd58 100644
--- a/proxy/tproxy/server.go
+++ b/proxy/tproxy/server.go
@@ -106,6 +106,7 @@ func (s *TProxy) serveSession(session *Session) {
 	dstPC, dialer, writeTo, err := s.proxy.DialUDP("udp", session.dst.String())
 	if err != nil {
 		log.F("[tproxyu] dial to %s error: %v", session.dst, err)
+		nm.Delete(session.key)
 		return
 	}
 	defer dstPC.Close()
diff --git a/proxy/udp/udp.go b/proxy/udp/udp.go
index 6a0f9c4..80ab3a8 100644
--- a/proxy/udp/udp.go
+++ b/proxy/udp/udp.go
@@ -94,6 +94,7 @@ func (s *UDP) serveSession(session *Session) {
 	dstPC, dialer, writeTo, err := s.proxy.DialUDP("udp", session.src.String())
 	if err != nil {
 		log.F("[udp] remote dial error: %v", err)
+		nm.Delete(session.key)
 		return
 	}
 	defer dstPC.Close()
diff --git a/proxy/unix/server.go b/proxy/unix/server.go
index 6671ba2..dc2d891 100644
--- a/proxy/unix/server.go
+++ b/proxy/unix/server.go
@@ -143,6 +143,7 @@ func (s *Unix) serveSession(session *Session) {
 	dstPC, dialer, writeTo, err := s.proxy.DialUDP("udp", "")
 	if err != nil {
 		log.F("[unix] remote dial error: %v", err)
+		nm.Delete(session.key)
 		return
 	}
 	defer dstPC.Close()