diff --git a/test/integration/apiserver/admissionwebhook/apiserver_handler_test.go b/test/integration/apiserver/admissionwebhook/duplicate_owner_ref_test.go
similarity index 100%
rename from test/integration/apiserver/admissionwebhook/apiserver_handler_test.go
rename to test/integration/apiserver/admissionwebhook/duplicate_owner_ref_test.go
diff --git a/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go b/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go
new file mode 100644
index 00000000000..85dfa096bd5
--- /dev/null
+++ b/test/integration/apiserver/admissionwebhook/invalid_managedFields_test.go
@@ -0,0 +1,243 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package admissionwebhook
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	v1 "k8s.io/api/admission/v1"
+	admissionv1 "k8s.io/api/admissionregistration/v1"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/apiserver/pkg/endpoints/handlers/fieldmanager"
+	clientset "k8s.io/client-go/kubernetes"
+	restclient "k8s.io/client-go/rest"
+	kubeapiservertesting "k8s.io/kubernetes/cmd/kube-apiserver/app/testing"
+	"k8s.io/kubernetes/test/integration/framework"
+)
+
+// TestMutatingWebhookResetsInvalidManagedFields ensures that the API server
+// resets managedFields to their state before admission if a mutating webhook
+// patches create/update requests with invalid managedFields.
+func TestMutatingWebhookResetsInvalidManagedFields(t *testing.T) {
+	roots := x509.NewCertPool()
+	if !roots.AppendCertsFromPEM(localhostCert) {
+		t.Fatal("Failed to append Cert from PEM")
+	}
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
+	if err != nil {
+		t.Fatalf("Failed to build cert with error: %+v", err)
+	}
+
+	webhookServer := httptest.NewUnstartedServer(newInvalidManagedFieldsWebhookHandler(t))
+	webhookServer.TLS = &tls.Config{
+		RootCAs:      roots,
+		Certificates: []tls.Certificate{cert},
+	}
+	webhookServer.StartTLS()
+	defer webhookServer.Close()
+
+	s := kubeapiservertesting.StartTestServerOrDie(t,
+		kubeapiservertesting.NewDefaultTestServerOptions(), []string{
+			"--disable-admission-plugins=ServiceAccount",
+		}, framework.SharedEtcd())
+	defer s.TearDownFn()
+
+	recordedWarnings := &bytes.Buffer{}
+	warningWriter := restclient.NewWarningWriter(recordedWarnings, restclient.WarningWriterOptions{})
+	s.ClientConfig.WarningHandler = warningWriter
+	client := clientset.NewForConfigOrDie(s.ClientConfig)
+
+	if _, err := client.CoreV1().Pods("default").Create(
+		context.TODO(), invalidManagedFieldsMarkerFixture, metav1.CreateOptions{}); err != nil {
+		t.Fatal(err)
+	}
+	// make sure we delete the pod even on a failed test
+	defer func() {
+		if err := client.CoreV1().Pods("default").Delete(context.TODO(), invalidManagedFieldsMarkerFixture.Name, metav1.DeleteOptions{}); err != nil {
+			t.Fatalf("failed to delete marker pod: %v", err)
+		}
+	}()
+
+	fail := admissionv1.Fail
+	none := admissionv1.SideEffectClassNone
+	mutatingCfg, err := client.AdmissionregistrationV1().MutatingWebhookConfigurations().Create(context.TODO(), &admissionv1.MutatingWebhookConfiguration{
+		ObjectMeta: metav1.ObjectMeta{Name: "invalid-managedfields.admission.integration.test"},
+		Webhooks: []admissionv1.MutatingWebhook{{
+			Name: "invalid-managedfields.admission.integration.test",
+			ClientConfig: admissionv1.WebhookClientConfig{
+				URL:      &webhookServer.URL,
+				CABundle: localhostCert,
+			},
+			Rules: []admissionv1.RuleWithOperations{{
+				Operations: []admissionv1.OperationType{admissionv1.Create, admissionv1.Update},
+				Rule:       admissionv1.Rule{APIGroups: []string{""}, APIVersions: []string{"v1"}, Resources: []string{"pods"}},
+			}},
+			FailurePolicy:           &fail,
+			AdmissionReviewVersions: []string{"v1", "v1beta1"},
+			SideEffects:             &none,
+		}},
+	}, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		err := client.AdmissionregistrationV1().MutatingWebhookConfigurations().Delete(context.TODO(), mutatingCfg.GetName(), metav1.DeleteOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	var pod *corev1.Pod
+	var lastErr string
+	// TODO(kwiesmueller): define warning format in the apiserver and use here
+	expectedWarning := fieldmanager.InvalidManagedFieldsAfterMutatingAdmissionWarningFormat
+
+	// Make sure reset happens on patch requests
+	// wait until new webhook is called
+	if err := wait.PollImmediate(time.Millisecond*5, wait.ForeverTestTimeout, func() (bool, error) {
+		pod, err = client.CoreV1().Pods("default").Patch(context.TODO(), invalidManagedFieldsMarkerFixture.Name, types.JSONPatchType, []byte("[]"), metav1.PatchOptions{})
+		if err != nil {
+			return false, err
+		}
+		if warningWriter.WarningCount() == 0 {
+			lastErr = fmt.Sprintf("no warning, managedFields: %v", pod.ManagedFields)
+			return false, nil
+		}
+		if !strings.Contains(recordedWarnings.String(), expectedWarning) {
+			lastErr = fmt.Sprintf("unexpected warning, expected: %v, got: %v",
+				expectedWarning, recordedWarnings.String())
+			return false, nil
+		}
+		if err := expectValidManagedFields(pod.ManagedFields); err != nil {
+			lastErr = err.Error()
+			return false, nil
+		}
+		return true, nil
+	}); err != nil {
+		t.Fatalf("failed to wait for apiserver handling webhook mutation: %v, last error: %v", err, lastErr)
+	}
+	if warningWriter.WarningCount() != 1 {
+		t.Errorf("expected one warning, got: %v", warningWriter.WarningCount())
+	}
+	recordedWarnings.Reset()
+
+	// Make sure dedup happens in update requests
+	pod, err = client.CoreV1().Pods("default").Update(context.TODO(), pod, metav1.UpdateOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if warningWriter.WarningCount() != 2 {
+		t.Errorf("expected two warnings, got: %v", warningWriter.WarningCount())
+	}
+	if !strings.Contains(recordedWarnings.String(), expectedWarning) {
+		t.Errorf("unexpected warning, expected: %v, got: %v",
+			expectedWarning, recordedWarnings.String())
+	}
+	if err := expectValidManagedFields(pod.ManagedFields); err != nil {
+		t.Error(err)
+	}
+	recordedWarnings.Reset()
+
+}
+
+func expectValidManagedFields(managedFields []metav1.ManagedFieldsEntry) error {
+	for i, managed := range managedFields {
+		// TODO: define what we want to validate
+		if len(managed.APIVersion) < 1 {
+			return fmt.Errorf(".metadata.managedFields[%d] is invalid: missing apiVersion", i)
+		}
+		if len(managed.FieldsType) < 1 {
+			return fmt.Errorf(".metadata.managedFields[%d] is invalid: missing fieldsType", i)
+		}
+		if len(managed.Manager) < 1 {
+			return fmt.Errorf(".metadata.managedFields[%d] is invalid: missing manager", i)
+		}
+		if managed.FieldsV1 == nil {
+			return fmt.Errorf(".metadata.managedFields[%d] is invalid: missing fieldsV1", i)
+		}
+	}
+	return nil
+}
+
+func newInvalidManagedFieldsWebhookHandler(t *testing.T) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer r.Body.Close()
+		data, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+		}
+		review := v1.AdmissionReview{}
+		if err := json.Unmarshal(data, &review); err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+		}
+
+		if len(review.Request.Object.Raw) == 0 {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+		pod := &corev1.Pod{}
+		if err := json.Unmarshal(review.Request.Object.Raw, pod); err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		review.Response = &v1.AdmissionResponse{
+			Allowed: true,
+			UID:     review.Request.UID,
+			Result:  &metav1.Status{Message: "admitted"},
+		}
+
+		if len(pod.ManagedFields) != 0 {
+			t.Logf("corrupting managedFields %v", pod.ManagedFields)
+			review.Response.Patch = []byte(`[{"op":"remove","path":"metadata/managedFields/0/apiVersion"},{"op":"remove","path":"/metadata/managedFields/0/fieldsType"}]`)
+			jsonPatch := v1.PatchTypeJSONPatch
+			review.Response.PatchType = &jsonPatch
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		if err := json.NewEncoder(w).Encode(review); err != nil {
+			t.Errorf("Marshal of response failed with error: %v", err)
+		}
+	})
+}
+
+var invalidManagedFieldsMarkerFixture = &corev1.Pod{
+	ObjectMeta: metav1.ObjectMeta{
+		Namespace: "default",
+		Name:      "invalid-managedfields-test-marker",
+	},
+	Spec: corev1.PodSpec{
+		Containers: []corev1.Container{{
+			Name:  "fake-name",
+			Image: "fakeimage",
+		}},
+	},
+}