diff --git a/protocol/shadowsocks/service.go b/protocol/shadowsocks/service.go
index 14716a5..63d4076 100644
--- a/protocol/shadowsocks/service.go
+++ b/protocol/shadowsocks/service.go
@@ -41,7 +41,6 @@ func (e *ServerConnError) Error() string {
 }
 
 type ServerPacketError struct {
-	N.PacketConn
 	Source M.Socksaddr
 	Cause  error
 }
diff --git a/protocol/shadowsocks/shadowaead/service.go b/protocol/shadowsocks/shadowaead/service.go
index dd47ce9..8db96b3 100644
--- a/protocol/shadowsocks/shadowaead/service.go
+++ b/protocol/shadowsocks/shadowaead/service.go
@@ -201,7 +201,7 @@ func (c *serverConn) WriterReplaceable() bool {
 func (s *Service) NewPacket(conn N.PacketConn, buffer *buf.Buffer, metadata M.Metadata) error {
 	err := s.newPacket(conn, buffer, metadata)
 	if err != nil {
-		err = &shadowsocks.ServerPacketError{PacketConn: conn, Source: metadata.Source, Cause: err}
+		err = &shadowsocks.ServerPacketError{Source: metadata.Source, Cause: err}
 	}
 	return err
 }
diff --git a/protocol/shadowsocks/shadowaead_2022/protocol.go b/protocol/shadowsocks/shadowaead_2022/protocol.go
index e9ec7aa..999cef9 100644
--- a/protocol/shadowsocks/shadowaead_2022/protocol.go
+++ b/protocol/shadowsocks/shadowaead_2022/protocol.go
@@ -67,7 +67,6 @@ var List = []string{
 func New(method string, pskList [][]byte, password string, secureRNG io.Reader) (shadowsocks.Method, error) {
 	m := &Method{
 		name:         method,
-		pskList:      pskList,
 		secureRNG:    secureRNG,
 		replayFilter: replay.NewCuckoo(60),
 	}
@@ -125,6 +124,7 @@ func New(method string, pskList [][]byte, password string, secureRNG io.Reader)
 		m.udpCipher = newXChacha20Poly1305(pskList[0])
 	}
 
+	m.pskList = pskList
 	return m, nil
 }
 
@@ -479,9 +479,6 @@ func (c *clientPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksad
 	if err != nil {
 		return err
 	}
-	if err != nil {
-		return err
-	}
 	if c.udpCipher != nil {
 		c.udpCipher.Seal(buffer.Index(dataIndex), buffer.To(dataIndex), buffer.From(dataIndex), nil)
 		buffer.Extend(c.udpCipher.Overhead())
@@ -687,9 +684,6 @@ func (c *clientPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	if err != nil {
 		return
 	}
-	if err != nil {
-		return
-	}
 	if c.udpCipher != nil {
 		c.udpCipher.Seal(buffer.Index(dataIndex), buffer.To(dataIndex), buffer.From(dataIndex), nil)
 		buffer.Extend(c.udpCipher.Overhead())
diff --git a/protocol/shadowsocks/shadowaead_2022/service.go b/protocol/shadowsocks/shadowaead_2022/service.go
index e9a12f0..dd2d282 100644
--- a/protocol/shadowsocks/shadowaead_2022/service.go
+++ b/protocol/shadowsocks/shadowaead_2022/service.go
@@ -71,17 +71,14 @@ func NewService(method string, psk []byte, password string, secureRNG io.Reader,
 		s.constructor = newChacha20Poly1305
 	}
 
-	if len(psk) == s.keySaltLength {
-		s.psk = psk
-	} else if len(psk) != 0 {
-		if len(psk) < s.keySaltLength {
-			return nil, shadowsocks.ErrBadKey
-		}
-		s.psk = Key(psk, s.keySaltLength)
+	if len(psk) < s.keySaltLength {
+		return nil, shadowsocks.ErrBadKey
+	} else if len(psk) > s.keySaltLength {
+		psk = Key(psk, s.keySaltLength)
 	} else if password == "" {
 		return nil, ErrMissingPasswordPSK
 	} else {
-		s.psk = Key([]byte(password), s.keySaltLength)
+		psk = Key([]byte(password), s.keySaltLength)
 	}
 
 	switch method {
@@ -93,6 +90,7 @@ func NewService(method string, psk []byte, password string, secureRNG io.Reader,
 		s.udpCipher = newXChacha20Poly1305(psk)
 	}
 
+	s.psk = psk
 	return s, nil
 }
 
@@ -271,7 +269,7 @@ func (c *serverConn) WriterReplaceable() bool {
 func (s *Service) NewPacket(conn N.PacketConn, buffer *buf.Buffer, metadata M.Metadata) error {
 	err := s.newPacket(conn, buffer, metadata)
 	if err != nil {
-		err = &shadowsocks.ServerPacketError{PacketConn: conn, Source: metadata.Source, Cause: err}
+		err = &shadowsocks.ServerPacketError{Source: metadata.Source, Cause: err}
 	}
 	return err
 }
diff --git a/protocol/shadowsocks/shadowaead_2022/service_multi.go b/protocol/shadowsocks/shadowaead_2022/service_multi.go
index 9c0df4b..6269379 100644
--- a/protocol/shadowsocks/shadowaead_2022/service_multi.go
+++ b/protocol/shadowsocks/shadowaead_2022/service_multi.go
@@ -191,7 +191,7 @@ func (s *MultiService[U]) newConnection(ctx context.Context, conn net.Conn, meta
 func (s *MultiService[U]) NewPacket(conn N.PacketConn, buffer *buf.Buffer, metadata M.Metadata) error {
 	err := s.newPacket(conn, buffer, metadata)
 	if err != nil {
-		err = &shadowsocks.ServerPacketError{PacketConn: conn, Source: metadata.Source, Cause: err}
+		err = &shadowsocks.ServerPacketError{Source: metadata.Source, Cause: err}
 	}
 	return err
 }