diff --git a/app/proxyman/inbound/always.go b/app/proxyman/inbound/always.go
index 38c933f5..e6760357 100644
--- a/app/proxyman/inbound/always.go
+++ b/app/proxyman/inbound/always.go
@@ -7,9 +7,9 @@ import (
 	"v2ray.com/core/app/proxyman"
 	"v2ray.com/core/common"
 	"v2ray.com/core/common/dice"
+	"v2ray.com/core/common/errors"
 	"v2ray.com/core/common/mux"
 	"v2ray.com/core/common/net"
-	"v2ray.com/core/common/serial"
 	"v2ray.com/core/features/policy"
 	"v2ray.com/core/features/stats"
 	"v2ray.com/core/proxy"
@@ -137,17 +137,13 @@ func (h *AlwaysOnInboundHandler) Start() error {
 
 // Close implements common.Closable.
 func (h *AlwaysOnInboundHandler) Close() error {
-	var errors []interface{}
+	var errs []error
 	for _, worker := range h.workers {
-		if err := worker.Close(); err != nil {
-			errors = append(errors, err)
-		}
-	}
-	if err := h.mux.Close(); err != nil {
-		errors = append(errors, err)
+		errs = append(errs, worker.Close())
 	}
-	if len(errors) > 0 {
-		return newError("failed to close all resources").Base(newError(serial.Concat(errors...)))
+	errs = append(errs, h.mux.Close())
+	if err := errors.Combine(errs...); err != nil {
+		return newError("failed to close all resources").Base(err)
 	}
 	return nil
 }
diff --git a/app/proxyman/outbound/outbound.go b/app/proxyman/outbound/outbound.go
index 5cf838c9..ce5cc5c7 100644
--- a/app/proxyman/outbound/outbound.go
+++ b/app/proxyman/outbound/outbound.go
@@ -10,6 +10,7 @@ import (
 	"v2ray.com/core"
 	"v2ray.com/core/app/proxyman"
 	"v2ray.com/core/common"
+	"v2ray.com/core/common/errors"
 	"v2ray.com/core/features/outbound"
 )
 
@@ -64,15 +65,16 @@ func (m *Manager) Close() error {
 
 	m.running = false
 
+	var errs []error
 	for _, h := range m.taggedHandler {
-		h.Close()
+		errs = append(errs, h.Close())
 	}
 
 	for _, h := range m.untaggedHandlers {
-		h.Close()
+		errs = append(errs, h.Close())
 	}
 
-	return nil
+	return errors.Combine(errs...)
 }
 
 // GetDefaultHandler implements outbound.Manager.
diff --git a/app/reverse/reverse.go b/app/reverse/reverse.go
index ed3b41fb..88f15f79 100644
--- a/app/reverse/reverse.go
+++ b/app/reverse/reverse.go
@@ -7,6 +7,7 @@ import (
 
 	"v2ray.com/core"
 	"v2ray.com/core/common"
+	"v2ray.com/core/common/errors"
 	"v2ray.com/core/common/net"
 	"v2ray.com/core/features/outbound"
 	"v2ray.com/core/features/routing"
@@ -82,17 +83,14 @@ func (r *Reverse) Start() error {
 }
 
 func (r *Reverse) Close() error {
+	var errs []error
 	for _, b := range r.bridges {
-		if err := b.Close(); err != nil {
-			return err
-		}
+		errs = append(errs, b.Close())
 	}
 
 	for _, p := range r.portals {
-		if err := p.Close(); err != nil {
-			return err
-		}
+		errs = append(errs, p.Close())
 	}
 
-	return nil
+	return errors.Combine(errs...)
 }
diff --git a/common/errors/multi_error.go b/common/errors/multi_error.go
new file mode 100644
index 00000000..8f19c97a
--- /dev/null
+++ b/common/errors/multi_error.go
@@ -0,0 +1,30 @@
+package errors
+
+import (
+	"strings"
+)
+
+type multiError []error
+
+func (e multiError) Error() string {
+	var r strings.Builder
+	r.WriteString("multierr: ")
+	for _, err := range e {
+		r.WriteString(err.Error())
+		r.WriteString(" | ")
+	}
+	return r.String()
+}
+
+func Combine(maybeError ...error) error {
+	var errs multiError
+	for _, err := range maybeError {
+		if err != nil {
+			errs = append(errs, err)
+		}
+	}
+	if len(errs) == 0 {
+		return nil
+	}
+	return errs
+}
diff --git a/common/task/task.go b/common/task/task.go
index 26227b85..1b6a5319 100644
--- a/common/task/task.go
+++ b/common/task/task.go
@@ -2,26 +2,12 @@ package task
 
 import (
 	"context"
-	"strings"
 
-	"v2ray.com/core/common"
 	"v2ray.com/core/common/signal/semaphore"
 )
 
 type Task func() error
 
-type MultiError []error
-
-func (e MultiError) Error() string {
-	var r strings.Builder
-	common.Must2(r.WriteString("multierr: "))
-	for _, err := range e {
-		common.Must2(r.WriteString(err.Error()))
-		common.Must2(r.WriteString(" | "))
-	}
-	return r.String()
-}
-
 type executionContext struct {
 	ctx       context.Context
 	tasks     []Task
@@ -90,30 +76,6 @@ func Sequential(tasks ...Task) ExecutionOption {
 	}
 }
 
-func SequentialAll(tasks ...Task) ExecutionOption {
-	return func(c *executionContext) {
-		switch len(tasks) {
-		case 0:
-			return
-		case 1:
-			c.tasks = append(c.tasks, tasks[0])
-		default:
-			c.tasks = append(c.tasks, func() error {
-				var merr MultiError
-				for _, task := range tasks {
-					if err := task(); err != nil {
-						merr = append(merr, err)
-					}
-				}
-				if len(merr) == 0 {
-					return nil
-				}
-				return merr
-			})
-		}
-	}
-}
-
 func OnSuccess(task Task) ExecutionOption {
 	return func(c *executionContext) {
 		c.onSuccess = task
diff --git a/proxy/vmess/inbound/inbound.go b/proxy/vmess/inbound/inbound.go
index e9274e1a..5d6a05eb 100644
--- a/proxy/vmess/inbound/inbound.go
+++ b/proxy/vmess/inbound/inbound.go
@@ -139,9 +139,10 @@ func New(ctx context.Context, config *Config) (*Handler, error) {
 
 // Close implements common.Closable.
 func (h *Handler) Close() error {
-	return task.Run(
-		task.SequentialAll(
-			task.Close(h.clients), task.Close(h.sessionHistory), task.Close(h.usersByEmail)))()
+	return errors.Combine(
+		h.clients.Close(),
+		h.sessionHistory.Close(),
+		common.Close(h.usersByEmail))
 }
 
 // Network implements proxy.Inbound.Network().
@@ -290,9 +291,10 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection i
 	}
 
 	responseDone := func() error {
+		defer timer.SetTimeout(sessionPolicy.Timeouts.UplinkOnly)
+
 		writer := buf.NewBufferedWriter(buf.NewWriter(connection))
 		defer writer.Flush()
-		defer timer.SetTimeout(sessionPolicy.Timeouts.UplinkOnly)
 
 		response := &protocol.ResponseHeader{
 			Command: h.generateCommand(ctx, request),