diff --git a/event.go b/event.go
index 7538e66..8c9c523 100644
--- a/event.go
+++ b/event.go
@@ -466,7 +466,8 @@ func (e *Event) Err(err error) *Event {
 	if e.stack && ErrorStackMarshaler != nil {
 		switch m := ErrorStackMarshaler(err).(type) {
 		case nil:
-			return e
+			// ErrorStackMarshaler returned nil — the error has no stack trace to
+			// attach. Fall through and still log the error via AnErr below.
 		case LogObjectMarshaler:
 			e = e.Object(ErrorStackFieldName, m)
 		case error:
diff --git a/event_test.go b/event_test.go
index 1446947..08ed5ea 100644
--- a/event_test.go
+++ b/event_test.go
@@ -720,7 +720,13 @@ func TestEvent_ErrWithStackMarshalerNil(t *testing.T) {
 	log.Log().Stack().Err(err).Msg("test message")
 
 	got := buf.String()
-	want := `{"message":"test message"}` + "\n" // No fields because stack marshaler returned nil
+	// When ErrorStackMarshaler returns nil (no stack trace available for this
+	// error), Err() must still log the error value via AnErr.  Without a stack
+	// field, the output is the same as if Stack() had not been called.
+	// Regression test for https://github.com/rs/zerolog/issues/762:
+	// commit f6fbd33 introduced a `case nil: return e` branch that silently
+	// swallowed the error instead of falling through to AnErr.
+	want := `{"error":"test error","message":"test message"}` + "\n"
 	if got != want {
 		t.Errorf("Event.Err() with nil stack marshaler = %q, want %q", got, want)
 	}