diff --git a/silence/silence.go b/silence/silence.go
index 37eadc60..06a27cf6 100644
--- a/silence/silence.go
+++ b/silence/silence.go
@@ -518,9 +518,6 @@ func matchesEmpty(m *pb.Matcher) bool {
 }
 
 func validateSilence(s *pb.Silence) error {
-	if s.Id == "" {
-		return errors.New("ID missing")
-	}
 	if len(s.Matchers) == 0 {
 		return errors.New("at least one matcher required")
 	}
@@ -544,9 +541,6 @@ func validateSilence(s *pb.Silence) error {
 	if s.EndsAt.Before(s.StartsAt) {
 		return errors.New("end time must not be before start time")
 	}
-	if s.UpdatedAt.IsZero() {
-		return errors.New("invalid zero update timestamp")
-	}
 	return nil
 }
 
@@ -571,15 +565,9 @@ func (s *Silences) toMeshSilence(sil *pb.Silence) *pb.MeshSilence {
 	}
 }
 
-func (s *Silences) setSilence(sil *pb.Silence, now time.Time, skipValidate bool) error {
+func (s *Silences) setSilence(sil *pb.Silence, now time.Time) error {
 	sil.UpdatedAt = now
 
-	if !skipValidate {
-		if err := validateSilence(sil); err != nil {
-			return fmt.Errorf("silence invalid: %w", err)
-		}
-	}
-
 	msil := s.toMeshSilence(sil)
 	b, err := marshalMeshSilence(msil)
 	if err != nil {
@@ -611,13 +599,21 @@ func (s *Silences) Set(sil *pb.Silence) error {
 	defer s.mtx.Unlock()
 
 	now := s.nowUTC()
+	if sil.StartsAt.IsZero() {
+		sil.StartsAt = now
+	}
+
+	if err := validateSilence(sil); err != nil {
+		return fmt.Errorf("invalid silence: %w", err)
+	}
+
 	prev, ok := s.getSilence(sil.Id)
 	if sil.Id != "" && !ok {
 		return ErrNotFound
 	}
 
 	if ok && canUpdate(prev, sil, now) {
-		return s.setSilence(sil, now, false)
+		return s.setSilence(sil, now)
 	}
 
 	// If we got here it's either a new silence or a replacing one (which would
@@ -647,7 +643,7 @@ func (s *Silences) Set(sil *pb.Silence) error {
 		sil.StartsAt = now
 	}
 
-	return s.setSilence(sil, now, false)
+	return s.setSilence(sil, now)
 }
 
 // canUpdate returns true if silence a can be updated to b without
@@ -705,10 +701,7 @@ func (s *Silences) expire(id string) error {
 		sil.StartsAt = now
 		sil.EndsAt = now
 	}
-
-	// Skip validation of the silence when expiring it. Without this, silences created
-	// with valid UTF-8 matchers cannot be expired when Alertmanager is run in classic mode.
-	return s.setSilence(sil, now, true)
+	return s.setSilence(sil, now)
 }
 
 // QueryParam expresses parameters along which silences are queried.
diff --git a/silence/silence_test.go b/silence/silence_test.go
index b77eca83..c9a635f4 100644
--- a/silence/silence_test.go
+++ b/silence/silence_test.go
@@ -295,7 +295,7 @@ func TestSilencesSetSilence(t *testing.T) {
 	func() {
 		s.mtx.Lock()
 		defer s.mtx.Unlock()
-		require.NoError(t, s.setSilence(sil, nowpb, false))
+		require.NoError(t, s.setSilence(sil, nowpb))
 	}()
 
 	// Ensure broadcast was called.
@@ -468,6 +468,19 @@ func TestSilenceSet(t *testing.T) {
 		},
 	}
 	require.Equal(t, want, s.st, "unexpected state after silence creation")
+
+	// Updating an existing silence with an invalid silence should not expire
+	// the original silence.
+	clock.Add(time.Millisecond)
+	sil8 := cloneSilence(sil7)
+	sil8.EndsAt = time.Time{}
+	require.EqualError(t, s.Set(sil8), "invalid silence: invalid zero end timestamp")
+
+	// sil7 should not be expired because the update failed.
+	clock.Add(time.Millisecond)
+	sil7, err = s.QueryOne(QIDs(sil7.Id))
+	require.NoError(t, err)
+	require.Equal(t, types.SilenceStateActive, getState(sil7, s.nowUTC()))
 }
 
 func TestSilenceLimits(t *testing.T) {
@@ -643,11 +656,15 @@ func TestSilencesSetFail(t *testing.T) {
 		err string
 	}{
 		{
-			s:   &pb.Silence{Id: "some_id"},
+			s: &pb.Silence{
+				Id:       "some_id",
+				Matchers: []*pb.Matcher{{Name: "a", Pattern: "b"}},
+				EndsAt:   clock.Now().Add(5 * time.Minute),
+			},
 			err: ErrNotFound.Error(),
 		}, {
 			s:   &pb.Silence{}, // Silence without matcher.
-			err: "silence invalid",
+			err: "invalid silence",
 		},
 	}
 	for _, c := range cases {
@@ -1488,18 +1505,6 @@ func TestValidateSilence(t *testing.T) {
 			},
 			err: "",
 		},
-		{
-			s: &pb.Silence{
-				Id: "",
-				Matchers: []*pb.Matcher{
-					{Name: "a", Pattern: "b"},
-				},
-				StartsAt:  validTimestamp,
-				EndsAt:    validTimestamp,
-				UpdatedAt: validTimestamp,
-			},
-			err: "ID missing",
-		},
 		{
 			s: &pb.Silence{
 				Id:        "some_id",
@@ -1572,18 +1577,6 @@ func TestValidateSilence(t *testing.T) {
 			},
 			err: "invalid zero end timestamp",
 		},
-		{
-			s: &pb.Silence{
-				Id: "some_id",
-				Matchers: []*pb.Matcher{
-					{Name: "a", Pattern: "b"},
-				},
-				StartsAt:  validTimestamp,
-				EndsAt:    validTimestamp,
-				UpdatedAt: zeroTimestamp,
-			},
-			err: "invalid zero update timestamp",
-		},
 	}
 	for _, c := range cases {
 		checkErr(t, c.err, validateSilence(c.s))
diff --git a/test/with_api_v2/acceptance/utf8_test.go b/test/with_api_v2/acceptance/utf8_test.go
index 6c12b2f7..c0c1dce2 100644
--- a/test/with_api_v2/acceptance/utf8_test.go
+++ b/test/with_api_v2/acceptance/utf8_test.go
@@ -267,7 +267,7 @@ receivers:
 
 	_, err := am.Client().Silence.PostSilences(silenceParams)
 	require.Error(t, err)
-	require.True(t, strings.Contains(err.Error(), "silence invalid: invalid label matcher"))
+	require.True(t, strings.Contains(err.Error(), "invalid silence: invalid label matcher"))
 }
 
 func TestSendAlertsToUTF8Route(t *testing.T) {