diff --git a/runtime/observatory/tests/service/regress_44859_test.dart b/runtime/observatory/tests/service/regress_44859_test.dart
new file mode 100644
index 00000000000..81120700d35
--- /dev/null
+++ b/runtime/observatory/tests/service/regress_44859_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:observatory/service_io.dart';
+import 'package:test/test.dart';
+import 'test_helper.dart';
+
+void script() {}
+
+var tests = <IsolateTest>[
+  (Isolate isolate) async {
+    Map metrics = await isolate.refreshDartMetrics();
+    expect(metrics.length, 0);
+  },
+];
+
+main(args) => runIsolateTests(args, tests, testeeBefore: script);
diff --git a/runtime/observatory_2/tests/service_2/regress_44859_test.dart b/runtime/observatory_2/tests/service_2/regress_44859_test.dart
new file mode 100644
index 00000000000..46bf69dbba2
--- /dev/null
+++ b/runtime/observatory_2/tests/service_2/regress_44859_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:observatory_2/service_io.dart';
+import 'package:test/test.dart';
+import 'test_helper.dart';
+
+void script() {}
+
+var tests = <IsolateTest>[
+  (Isolate isolate) async {
+    Map metrics = await isolate.refreshDartMetrics();
+    expect(metrics.length, 0);
+  },
+];
+
+main(args) => runIsolateTests(args, tests, testeeBefore: script);
diff --git a/runtime/vm/service.cc b/runtime/vm/service.cc
index a4a8c0bb807..4827248c236 100644
--- a/runtime/vm/service.cc
+++ b/runtime/vm/service.cc
@@ -3584,6 +3584,8 @@ static bool HandleNativeMetric(Thread* thread, JSONStream* js, const char* id) {
 static bool HandleDartMetricsList(Thread* thread, JSONStream* js) {
   Zone* zone = thread->zone();
   const Class& metrics_cls = Class::Handle(zone, GetMetricsClass(thread));
+  const auto& error = metrics_cls.EnsureIsFinalized(Thread::Current());
+  ASSERT(error == Error::null());
   const String& print_metrics_name =
       String::Handle(String::New("_printMetrics"));
   ASSERT(!print_metrics_name.IsNull());