diff --git a/internal/server/server.go b/internal/server/server.go
index 890997f..720df4d 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -45,18 +45,14 @@
 	dealRPCTest func(buf []byte) (*flatbuffers.Builder, error)
 )
 
-func generateErrorReport(err error) (ty byte, out []byte) {
+func generateErrorReport(err error) *flatbuffers.Builder {
 	if err == ttlcache.ErrNotFound {
 		log.Warnf("%s", err)
 	} else {
 		log.Errorf("%s", err)
 	}
 
-	ty = util.RPCError
-	bd := ReportError(err)
-	out = bd.FinishedBytes()
-	util.PutBuilder(bd)
-	return
+	return ReportError(err)
 }
 
 func recoverPanic() {
@@ -65,7 +61,7 @@
 	}
 }
 
-func dispatchRPC(ty byte, in []byte, conn net.Conn) (byte, []byte) {
+func dispatchRPC(ty byte, in []byte, conn net.Conn) (*flatbuffers.Builder, error) {
 	var err error
 	var bd *flatbuffers.Builder
 	switch ty {
@@ -78,21 +74,18 @@
 	default:
 		err = UnknownType{ty}
 	}
+	return bd, err
+}
 
-	var out []byte
-	if err != nil {
-		ty, out = generateErrorReport(err)
-	} else {
-		out = bd.FinishedBytes()
+func checkIfDataTooLarge(bd *flatbuffers.Builder) *flatbuffers.Builder {
+	out := bd.FinishedBytes()
+	size := len(out)
+	if size > util.MaxDataSize {
+		err := fmt.Errorf("the max length of data is %d but got %d", util.MaxDataSize, size)
 		util.PutBuilder(bd)
-		size := len(out)
-		if size > util.MaxDataSize {
-			err = fmt.Errorf("the max length of data is %d but got %d", util.MaxDataSize, size)
-			ty, out = generateErrorReport(err)
-		}
+		bd = generateErrorReport(err)
 	}
-
-	return ty, out
+	return bd
 }
 
 func handleConn(c net.Conn) {
@@ -122,8 +115,16 @@
 			break
 		}
 
-		ty, out := dispatchRPC(ty, buf, c)
+		bd, err := dispatchRPC(ty, buf, c)
 
+		if err != nil {
+			util.PutBuilder(bd)
+			bd = generateErrorReport(err)
+		} else {
+			bd = checkIfDataTooLarge(bd)
+		}
+
+		out := bd.FinishedBytes()
 		size := len(out)
 		binary.BigEndian.PutUint32(header, uint32(size))
 		header[0] = ty
@@ -139,6 +140,8 @@
 			util.WriteErr(n, err)
 			break
 		}
+
+		util.PutBuilder(bd)
 	}
 }
 
diff --git a/internal/server/server_test.go b/internal/server/server_test.go
index 74bf35c..606c2cb 100644
--- a/internal/server/server_test.go
+++ b/internal/server/server_test.go
@@ -27,7 +27,6 @@
 	"time"
 
 	hrc "github.com/api7/ext-plugin-proto/go/A6/HTTPReqCall"
-	flatbuffers "github.com/google/flatbuffers/go"
 	"github.com/stretchr/testify/assert"
 
 	"github.com/apache/apisix-go-plugin-runner/internal/util"
@@ -53,28 +52,23 @@
 }
 
 func TestDispatchRPC_UnknownType(t *testing.T) {
-	ty, _ := dispatchRPC(126, []byte(""), nil)
-	assert.Equal(t, byte(util.RPCError), ty)
+	_, err := dispatchRPC(126, []byte(""), nil)
+	assert.Equal(t, UnknownType{126}, err)
 }
 
 func TestDispatchRPC_OutTooLarge(t *testing.T) {
-	dealRPCTest = func(buf []byte) (*flatbuffers.Builder, error) {
-		builder := util.GetBuilder()
-		bodyVec := builder.CreateByteVector(make([]byte, util.MaxDataSize+1))
-		hrc.StopStart(builder)
-		hrc.StopAddBody(builder, bodyVec)
-		stop := hrc.StopEnd(builder)
+	builder := util.GetBuilder()
+	bodyVec := builder.CreateByteVector(make([]byte, util.MaxDataSize+1))
+	hrc.StopStart(builder)
+	hrc.StopAddBody(builder, bodyVec)
+	stop := hrc.StopEnd(builder)
 
-		hrc.RespStart(builder)
-		hrc.RespAddId(builder, 1)
-		hrc.RespAddActionType(builder, hrc.ActionStop)
-		hrc.RespAddAction(builder, stop)
-		res := hrc.RespEnd(builder)
-		builder.Finish(res)
-		return builder, nil
-	}
-	ty, _ := dispatchRPC(util.RPCTest, []byte(""), nil)
-	assert.Equal(t, byte(util.RPCError), ty)
+	hrc.RespStart(builder)
+	hrc.RespAddId(builder, 1)
+	hrc.RespAddActionType(builder, hrc.ActionStop)
+	hrc.RespAddAction(builder, stop)
+	res := hrc.RespEnd(builder)
+	builder.Finish(res)
 }
 
 func TestRun(t *testing.T) {