diff --git a/cmd/api/api.go b/cmd/api/api.go
index 83761fb8..e5d29f34 100644
--- a/cmd/api/api.go
+++ b/cmd/api/api.go
@@ -76,6 +76,8 @@ func HandleFunc(pattern string, handler http.HandlerFunc) {
 	http.HandleFunc(pattern, handler)
 }
 
+const StreamNotFound = "stream not found"
+
 var basePath string
 var log zerolog.Logger
 
diff --git a/cmd/api/ws.go b/cmd/api/ws.go
index ab42c537..f515eb82 100644
--- a/cmd/api/ws.go
+++ b/cmd/api/ws.go
@@ -14,7 +14,7 @@ type Message struct {
 	Value interface{} `json:"value,omitempty"`
 }
 
-type WSHandler func(tr *Transport, msg *Message)
+type WSHandler func(tr *Transport, msg *Message) error
 
 func HandleWS(msgType string, handler WSHandler) {
 	wsHandlers[msgType] = handler
@@ -84,7 +84,11 @@ func apiWS(w http.ResponseWriter, r *http.Request) {
 		}
 
 		if handler := wsHandlers[msg.Type]; handler != nil {
-			handler(tr, msg)
+			go func() {
+				if err = handler(tr, msg); err != nil {
+					tr.Write(&Message{Type: "error", Value: msg.Type + ": " + err.Error()})
+				}
+			}()
 		}
 	}
 
@@ -125,10 +129,6 @@ func (t *Transport) Close() {
 	}
 }
 
-func (t *Transport) Error(err error) {
-	t.Write(&Message{Type: "error", Value: err.Error()})
-}
-
 func (t *Transport) OnChange(f func()) {
 	t.onChange = f
 }
diff --git a/cmd/mjpeg/mjpeg.go b/cmd/mjpeg/mjpeg.go
index db6eff16..5c16999e 100644
--- a/cmd/mjpeg/mjpeg.go
+++ b/cmd/mjpeg/mjpeg.go
@@ -1,6 +1,7 @@
 package mjpeg
 
 import (
+	"errors"
 	"github.com/AlexxIT/go2rtc/cmd/api"
 	"github.com/AlexxIT/go2rtc/cmd/streams"
 	"github.com/AlexxIT/go2rtc/pkg/mjpeg"
@@ -20,6 +21,7 @@ func handlerKeyframe(w http.ResponseWriter, r *http.Request) {
 	src := r.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
+		http.Error(w, api.StreamNotFound, http.StatusNotFound)
 		return
 	}
 
@@ -60,6 +62,7 @@ func handlerStream(w http.ResponseWriter, r *http.Request) {
 	src := r.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
+		http.Error(w, api.StreamNotFound, http.StatusNotFound)
 		return
 	}
 
@@ -99,11 +102,11 @@ func handlerStream(w http.ResponseWriter, r *http.Request) {
 	//log.Trace().Msg("[api.mjpeg] close")
 }
 
-func handlerWS(tr *api.Transport, msg *api.Message) {
+func handlerWS(tr *api.Transport, _ *api.Message) error {
 	src := tr.Request.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
-		return
+		return errors.New(api.StreamNotFound)
 	}
 
 	cons := &mjpeg.Consumer{}
@@ -115,10 +118,12 @@ func handlerWS(tr *api.Transport, msg *api.Message) {
 
 	if err := stream.AddConsumer(cons); err != nil {
 		log.Error().Err(err).Caller().Send()
-		return
+		return err
 	}
 
 	tr.OnClose(func() {
 		stream.RemoveConsumer(cons)
 	})
+
+	return nil
 }
diff --git a/cmd/mp4/mp4.go b/cmd/mp4/mp4.go
index 5779d0ff..47aeeb82 100644
--- a/cmd/mp4/mp4.go
+++ b/cmd/mp4/mp4.go
@@ -32,6 +32,7 @@ func handlerKeyframe(w http.ResponseWriter, r *http.Request) {
 	src := r.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
+		http.Error(w, api.StreamNotFound, http.StatusNotFound)
 		return
 	}
 
@@ -73,6 +74,7 @@ func handlerMP4(w http.ResponseWriter, r *http.Request) {
 	src := r.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
+		http.Error(w, api.StreamNotFound, http.StatusNotFound)
 		return
 	}
 
diff --git a/cmd/mp4/ws.go b/cmd/mp4/ws.go
index 0c84eede..56b2965b 100644
--- a/cmd/mp4/ws.go
+++ b/cmd/mp4/ws.go
@@ -1,6 +1,7 @@
 package mp4
 
 import (
+	"errors"
 	"github.com/AlexxIT/go2rtc/cmd/api"
 	"github.com/AlexxIT/go2rtc/cmd/streams"
 	"github.com/AlexxIT/go2rtc/pkg/mp4"
@@ -10,11 +11,11 @@ import (
 
 const packetSize = 8192
 
-func handlerWS(tr *api.Transport, msg *api.Message) {
+func handlerWS(tr *api.Transport, msg *api.Message) error {
 	src := tr.Request.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
-		return
+		return errors.New(api.StreamNotFound)
 	}
 
 	cons := &mp4.Consumer{}
@@ -37,8 +38,7 @@ func handlerWS(tr *api.Transport, msg *api.Message) {
 
 	if err := stream.AddConsumer(cons); err != nil {
 		log.Warn().Err(err).Caller().Send()
-		tr.Error(err)
-		return
+		return err
 	}
 
 	tr.OnClose(func() {
@@ -50,20 +50,21 @@ func handlerWS(tr *api.Transport, msg *api.Message) {
 	data, err := cons.Init()
 	if err != nil {
 		log.Warn().Err(err).Caller().Send()
-		tr.Error(err)
-		return
+		return err
 	}
 
 	tr.Write(data)
 
 	cons.Start()
+
+	return nil
 }
 
-func handlerWS4(tr *api.Transport, msg *api.Message) {
+func handlerWS4(tr *api.Transport, msg *api.Message) error {
 	src := tr.Request.URL.Query().Get("src")
 	stream := streams.GetOrNew(src)
 	if stream == nil {
-		return
+		return errors.New(api.StreamNotFound)
 	}
 
 	cons := &mp4.Segment{}
@@ -80,12 +81,14 @@ func handlerWS4(tr *api.Transport, msg *api.Message) {
 
 	if err := stream.AddConsumer(cons); err != nil {
 		log.Error().Err(err).Caller().Send()
-		return
+		return err
 	}
 
 	tr.OnClose(func() {
 		stream.RemoveConsumer(cons)
 	})
+
+	return nil
 }
 
 func parseMedias(codecs string, parseAudio bool) (medias []*streamer.Media) {
diff --git a/cmd/webrtc/candidates.go b/cmd/webrtc/candidates.go
index 9a711cdc..677c0a15 100644
--- a/cmd/webrtc/candidates.go
+++ b/cmd/webrtc/candidates.go
@@ -78,13 +78,14 @@ func syncCanditates(answer string) (string, error) {
 	return string(data), nil
 }
 
-func candidateHandler(tr *api.Transport, msg *api.Message) {
+func candidateHandler(tr *api.Transport, msg *api.Message) error {
 	if tr.Consumer == nil {
-		return
+		return nil
 	}
 	if conn := tr.Consumer.(*webrtc.Conn); conn != nil {
 		s := msg.Value.(string)
 		log.Trace().Str("candidate", s).Msg("[webrtc] remote")
 		conn.AddCandidate(s)
 	}
+	return nil
 }
diff --git a/cmd/webrtc/webrtc.go b/cmd/webrtc/webrtc.go
index f975b839..394460de 100644
--- a/cmd/webrtc/webrtc.go
+++ b/cmd/webrtc/webrtc.go
@@ -1,6 +1,7 @@
 package webrtc
 
 import (
+	"errors"
 	"github.com/AlexxIT/go2rtc/cmd/api"
 	"github.com/AlexxIT/go2rtc/cmd/app"
 	"github.com/AlexxIT/go2rtc/cmd/streams"
@@ -65,11 +66,11 @@ var log zerolog.Logger
 
 var NewPConn func() (*pion.PeerConnection, error)
 
-func asyncHandler(tr *api.Transport, msg *api.Message) {
+func asyncHandler(tr *api.Transport, msg *api.Message) error {
 	src := tr.Request.URL.Query().Get("src")
 	stream := streams.Get(src)
 	if stream == nil {
-		return
+		return errors.New(api.StreamNotFound)
 	}
 
 	log.Debug().Str("url", src).Msg("[webrtc] new consumer")
@@ -80,8 +81,8 @@ func asyncHandler(tr *api.Transport, msg *api.Message) {
 	conn := new(webrtc.Conn)
 	conn.Conn, err = NewPConn()
 	if err != nil {
-		log.Error().Err(err).Caller().Msg("NewPConn")
-		return
+		log.Error().Err(err).Caller().Send()
+		return err
 	}
 
 	conn.UserAgent = tr.Request.UserAgent()
@@ -105,17 +106,15 @@ func asyncHandler(tr *api.Transport, msg *api.Message) {
 	log.Trace().Msgf("[webrtc] offer:\n%s", offer)
 
 	if err = conn.SetOffer(offer); err != nil {
-		log.Warn().Err(err).Caller().Msg("conn.SetOffer")
-		tr.Error(err)
-		return
+		log.Warn().Err(err).Caller().Send()
+		return err
 	}
 
 	// 2. AddConsumer, so we get new tracks
 	if err = stream.AddConsumer(conn); err != nil {
-		log.Warn().Err(err).Caller().Msg("stream.AddConsumer")
+		log.Warn().Err(err).Caller().Send()
 		_ = conn.Conn.Close()
-		tr.Error(err)
-		return
+		return err
 	}
 
 	conn.Init()
@@ -125,9 +124,8 @@ func asyncHandler(tr *api.Transport, msg *api.Message) {
 	log.Trace().Msgf("[webrtc] answer\n%s", answer)
 
 	if err != nil {
-		log.Error().Err(err).Caller().Msg("conn.GetAnswer")
-		tr.Error(err)
-		return
+		log.Error().Err(err).Caller().Send()
+		return err
 	}
 
 	tr.Consumer = conn
@@ -135,6 +133,8 @@ func asyncHandler(tr *api.Transport, msg *api.Message) {
 	tr.Write(&api.Message{Type: "webrtc/answer", Value: answer})
 
 	asyncCandidates(tr)
+
+	return nil
 }
 
 func syncHandler(w http.ResponseWriter, r *http.Request) {