diff --git a/cmd/libs/go2idl/client-gen/generators/generator_for_group.go b/cmd/libs/go2idl/client-gen/generators/generator_for_group.go
index afc4064efe4..21437a4e8b9 100644
--- a/cmd/libs/go2idl/client-gen/generators/generator_for_group.go
+++ b/cmd/libs/go2idl/client-gen/generators/generator_for_group.go
@@ -204,7 +204,8 @@ func setConfigDefaults(config *$.Config|raw$) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = $.codecs|raw$.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = $.codecs|raw$
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
@@ -232,11 +233,7 @@ func setConfigDefaults(config *$.Config|raw$) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	codec, ok := $.codecs|raw$.SerializerForFileExtension("json")
-	if !ok {
-		return $.Errorf|raw$("unable to find serializer for JSON")
-	}
-	config.Codec = codec
+	config.NegotiatedSerializer = $.codecs|raw$
 
 	if config.QPS == 0 {
 		config.QPS = 5
diff --git a/cmd/libs/go2idl/client-gen/testoutput/clientset_generated/test_internalclientset/typed/testgroup.k8s.io/unversioned/testgroup_client.go b/cmd/libs/go2idl/client-gen/testoutput/clientset_generated/test_internalclientset/typed/testgroup.k8s.io/unversioned/testgroup_client.go
index 56d08722b3e..f870a64d889 100644
--- a/cmd/libs/go2idl/client-gen/testoutput/clientset_generated/test_internalclientset/typed/testgroup.k8s.io/unversioned/testgroup_client.go
+++ b/cmd/libs/go2idl/client-gen/testoutput/clientset_generated/test_internalclientset/typed/testgroup.k8s.io/unversioned/testgroup_client.go
@@ -80,7 +80,8 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/api/testapi/testapi.go b/pkg/api/testapi/testapi.go
index bbbe0367e98..8bec17e33e3 100644
--- a/pkg/api/testapi/testapi.go
+++ b/pkg/api/testapi/testapi.go
@@ -45,13 +45,14 @@ import (
 )
 
 var (
-	Groups      = make(map[string]TestGroup)
-	Default     TestGroup
-	Autoscaling TestGroup
-	Batch       TestGroup
-	Extensions  TestGroup
-	Apps        TestGroup
-	Federation  TestGroup
+	Groups               = make(map[string]TestGroup)
+	Default              TestGroup
+	Autoscaling          TestGroup
+	Batch                TestGroup
+	Extensions           TestGroup
+	Apps                 TestGroup
+	Federation           TestGroup
+	NegotiatedSerializer = api.Codecs
 )
 
 type TestGroup struct {
diff --git a/pkg/client/clientset_generated/internalclientset/typed/batch/unversioned/batch_client.go b/pkg/client/clientset_generated/internalclientset/typed/batch/unversioned/batch_client.go
index e42c2d84a6e..58b67ceda07 100644
--- a/pkg/client/clientset_generated/internalclientset/typed/batch/unversioned/batch_client.go
+++ b/pkg/client/clientset_generated/internalclientset/typed/batch/unversioned/batch_client.go
@@ -80,7 +80,8 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/clientset_generated/internalclientset/typed/core/unversioned/core_client.go b/pkg/client/clientset_generated/internalclientset/typed/core/unversioned/core_client.go
index 9250a2261b5..41aee4cf654 100644
--- a/pkg/client/clientset_generated/internalclientset/typed/core/unversioned/core_client.go
+++ b/pkg/client/clientset_generated/internalclientset/typed/core/unversioned/core_client.go
@@ -155,7 +155,8 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/clientset_generated/internalclientset/typed/extensions/unversioned/extensions_client.go b/pkg/client/clientset_generated/internalclientset/typed/extensions/unversioned/extensions_client.go
index d8b97a05ed9..5c979161256 100644
--- a/pkg/client/clientset_generated/internalclientset/typed/extensions/unversioned/extensions_client.go
+++ b/pkg/client/clientset_generated/internalclientset/typed/extensions/unversioned/extensions_client.go
@@ -110,7 +110,8 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/clientset_generated/release_1_2/typed/core/v1/core_client.go b/pkg/client/clientset_generated/release_1_2/typed/core/v1/core_client.go
index 886d556b5dd..6c2874e386d 100644
--- a/pkg/client/clientset_generated/release_1_2/typed/core/v1/core_client.go
+++ b/pkg/client/clientset_generated/release_1_2/typed/core/v1/core_client.go
@@ -149,7 +149,8 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/clientset_generated/release_1_2/typed/extensions/v1beta1/extensions_client.go b/pkg/client/clientset_generated/release_1_2/typed/extensions/v1beta1/extensions_client.go
index af3348a3357..86cc6a9ce27 100644
--- a/pkg/client/clientset_generated/release_1_2/typed/extensions/v1beta1/extensions_client.go
+++ b/pkg/client/clientset_generated/release_1_2/typed/extensions/v1beta1/extensions_client.go
@@ -114,7 +114,8 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
+
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/clientset_generated/release_1_3/typed/core/v1/core_client.go b/pkg/client/clientset_generated/release_1_3/typed/core/v1/core_client.go
index c6b0cfbfe22..6c2874e386d 100644
--- a/pkg/client/clientset_generated/release_1_3/typed/core/v1/core_client.go
+++ b/pkg/client/clientset_generated/release_1_3/typed/core/v1/core_client.go
@@ -17,7 +17,6 @@ limitations under the License.
 package v1
 
 import (
-	fmt "fmt"
 	api "k8s.io/kubernetes/pkg/api"
 	registered "k8s.io/kubernetes/pkg/apimachinery/registered"
 	restclient "k8s.io/kubernetes/pkg/client/restclient"
@@ -150,11 +149,7 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	codec, ok := api.Codecs.SerializerForFileExtension("json")
-	if !ok {
-		return fmt.Errorf("unable to find serializer for JSON")
-	}
-	config.Codec = codec
+	config.NegotiatedSerializer = api.Codecs
 
 	if config.QPS == 0 {
 		config.QPS = 5
diff --git a/pkg/client/clientset_generated/release_1_3/typed/extensions/v1beta1/extensions_client.go b/pkg/client/clientset_generated/release_1_3/typed/extensions/v1beta1/extensions_client.go
index ebbe0a2f8b5..86cc6a9ce27 100644
--- a/pkg/client/clientset_generated/release_1_3/typed/extensions/v1beta1/extensions_client.go
+++ b/pkg/client/clientset_generated/release_1_3/typed/extensions/v1beta1/extensions_client.go
@@ -17,7 +17,6 @@ limitations under the License.
 package v1beta1
 
 import (
-	fmt "fmt"
 	api "k8s.io/kubernetes/pkg/api"
 	registered "k8s.io/kubernetes/pkg/apimachinery/registered"
 	restclient "k8s.io/kubernetes/pkg/client/restclient"
@@ -115,11 +114,7 @@ func setConfigDefaults(config *restclient.Config) error {
 	config.GroupVersion = &copyGroupVersion
 	//}
 
-	codec, ok := api.Codecs.SerializerForFileExtension("json")
-	if !ok {
-		return fmt.Errorf("unable to find serializer for JSON")
-	}
-	config.Codec = codec
+	config.NegotiatedSerializer = api.Codecs
 
 	if config.QPS == 0 {
 		config.QPS = 5
diff --git a/pkg/client/restclient/client.go b/pkg/client/restclient/client.go
index b66884f91ab..aab02d8b8dc 100644
--- a/pkg/client/restclient/client.go
+++ b/pkg/client/restclient/client.go
@@ -63,7 +63,7 @@ type RESTClient struct {
 // NewRESTClient creates a new RESTClient. This client performs generic REST functions
 // such as Get, Put, Post, and Delete on specified paths.  Codec controls encoding and
 // decoding of responses from the server.
-func NewRESTClient(baseURL *url.URL, versionedAPIPath string, config ContentConfig, maxQPS float32, maxBurst int, rateLimiter flowcontrol.RateLimiter, client *http.Client) *RESTClient {
+func NewRESTClient(baseURL *url.URL, versionedAPIPath string, config ContentConfig, maxQPS float32, maxBurst int, rateLimiter flowcontrol.RateLimiter, client *http.Client) (*RESTClient, error) {
 	base := *baseURL
 	if !strings.HasSuffix(base.Path, "/") {
 		base.Path += "/"
@@ -90,7 +90,7 @@ func NewRESTClient(baseURL *url.URL, versionedAPIPath string, config ContentConf
 		contentConfig:    config,
 		Throttle:         throttle,
 		Client:           client,
-	}
+	}, nil
 }
 
 // GetRateLimiter returns rate limier for a given client, or nil if it's called on a nil client
@@ -122,7 +122,8 @@ func readExpBackoffConfig() BackoffManager {
 // Verb begins a request with a verb (GET, POST, PUT, DELETE).
 //
 // Example usage of RESTClient's request building interface:
-// c := NewRESTClient(url, codec)
+// c, err := NewRESTClient(...)
+// if err != nil { ... }
 // resp, err := c.Verb("GET").
 //  Path("pods").
 //  SelectorParam("labels", "area=staging").
diff --git a/pkg/client/restclient/config.go b/pkg/client/restclient/config.go
index c1928de0818..5ecfe061a38 100644
--- a/pkg/client/restclient/config.go
+++ b/pkg/client/restclient/config.go
@@ -130,9 +130,15 @@ type ContentConfig struct {
 	// a RESTClient directly. When initializing a Client, will be set with the default
 	// code version.
 	GroupVersion *unversioned.GroupVersion
+	// NegotiatedSerializer is used for obtaining encoders and decoders for multiple
+	// supported media types.
+	NegotiatedSerializer runtime.NegotiatedSerializer
+
 	// Codec specifies the encoding and decoding behavior for runtime.Objects passed
 	// to a RESTClient or Client. Required when initializing a RESTClient, optional
 	// when initializing a Client.
+	//
+	// DEPRECATED: Please use NegotiatedSerializer instead.
 	Codec runtime.Codec
 }
 
@@ -144,8 +150,8 @@ func RESTClientFor(config *Config) (*RESTClient, error) {
 	if config.GroupVersion == nil {
 		return nil, fmt.Errorf("GroupVersion is required when initializing a RESTClient")
 	}
-	if config.Codec == nil {
-		return nil, fmt.Errorf("Codec is required when initializing a RESTClient")
+	if config.NegotiatedSerializer == nil {
+		return nil, fmt.Errorf("NegotiatedSerializer is required when initializing a RESTClient")
 	}
 
 	baseURL, versionedAPIPath, err := defaultServerUrlFor(config)
@@ -163,16 +169,14 @@ func RESTClientFor(config *Config) (*RESTClient, error) {
 		httpClient = &http.Client{Transport: transport}
 	}
 
-	client := NewRESTClient(baseURL, versionedAPIPath, config.ContentConfig, config.QPS, config.Burst, config.RateLimiter, httpClient)
-
-	return client, nil
+	return NewRESTClient(baseURL, versionedAPIPath, config.ContentConfig, config.QPS, config.Burst, config.RateLimiter, httpClient)
 }
 
 // UnversionedRESTClientFor is the same as RESTClientFor, except that it allows
 // the config.Version to be empty.
 func UnversionedRESTClientFor(config *Config) (*RESTClient, error) {
-	if config.Codec == nil {
-		return nil, fmt.Errorf("Codec is required when initializing a RESTClient")
+	if config.NegotiatedSerializer == nil {
+		return nil, fmt.Errorf("NeogitatedSerializer is required when initializing a RESTClient")
 	}
 
 	baseURL, versionedAPIPath, err := defaultServerUrlFor(config)
@@ -196,8 +200,7 @@ func UnversionedRESTClientFor(config *Config) (*RESTClient, error) {
 		versionConfig.GroupVersion = &v
 	}
 
-	client := NewRESTClient(baseURL, versionedAPIPath, versionConfig, config.QPS, config.Burst, config.RateLimiter, httpClient)
-	return client, nil
+	return NewRESTClient(baseURL, versionedAPIPath, versionConfig, config.QPS, config.Burst, config.RateLimiter, httpClient)
 }
 
 // SetKubernetesDefaults sets default values on the provided client config for accessing the
diff --git a/pkg/client/restclient/config_test.go b/pkg/client/restclient/config_test.go
index 1a1dd422b4f..029e64253ba 100644
--- a/pkg/client/restclient/config_test.go
+++ b/pkg/client/restclient/config_test.go
@@ -87,13 +87,13 @@ func TestSetKubernetesDefaultsUserAgent(t *testing.T) {
 }
 
 func TestRESTClientRequires(t *testing.T) {
-	if _, err := RESTClientFor(&Config{Host: "127.0.0.1", ContentConfig: ContentConfig{Codec: testapi.Default.Codec()}}); err == nil {
+	if _, err := RESTClientFor(&Config{Host: "127.0.0.1", ContentConfig: ContentConfig{NegotiatedSerializer: testapi.NegotiatedSerializer}}); err == nil {
 		t.Errorf("unexpected non-error")
 	}
 	if _, err := RESTClientFor(&Config{Host: "127.0.0.1", ContentConfig: ContentConfig{GroupVersion: testapi.Default.GroupVersion()}}); err == nil {
 		t.Errorf("unexpected non-error")
 	}
-	if _, err := RESTClientFor(&Config{Host: "127.0.0.1", ContentConfig: ContentConfig{GroupVersion: testapi.Default.GroupVersion(), Codec: testapi.Default.Codec()}}); err != nil {
+	if _, err := RESTClientFor(&Config{Host: "127.0.0.1", ContentConfig: ContentConfig{GroupVersion: testapi.Default.GroupVersion(), NegotiatedSerializer: testapi.NegotiatedSerializer}}); err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
 }
diff --git a/pkg/client/restclient/request_test.go b/pkg/client/restclient/request_test.go
index 31f2f9fcf5e..b194b37778d 100644
--- a/pkg/client/restclient/request_test.go
+++ b/pkg/client/restclient/request_test.go
@@ -1308,5 +1308,9 @@ func testRESTClient(t testing.TB, srv *httptest.Server) *RESTClient {
 		}
 	}
 	versionedAPIPath := testapi.Default.ResourcePath("", "", "")
-	return NewRESTClient(baseURL, versionedAPIPath, ContentConfig{GroupVersion: testapi.Default.GroupVersion(), Codec: testapi.Default.Codec()}, 0, 0, nil, nil)
+	client, err := NewRESTClient(baseURL, versionedAPIPath, ContentConfig{GroupVersion: testapi.Default.GroupVersion(), Codec: testapi.Default.Codec()}, 0, 0, nil, nil)
+	if err != nil {
+		t.Fatalf("failed to create a client: %v", err)
+	}
+	return client
 }
diff --git a/pkg/client/unversioned/apps.go b/pkg/client/unversioned/apps.go
index a6612d75a93..c81c53d84ee 100644
--- a/pkg/client/unversioned/apps.go
+++ b/pkg/client/unversioned/apps.go
@@ -72,6 +72,7 @@ func setAppsDefaults(config *restclient.Config) error {
 	//}
 
 	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/unversioned/autoscaling.go b/pkg/client/unversioned/autoscaling.go
index c3ec1981030..7566042544f 100644
--- a/pkg/client/unversioned/autoscaling.go
+++ b/pkg/client/unversioned/autoscaling.go
@@ -73,6 +73,7 @@ func setAutoscalingDefaults(config *restclient.Config) error {
 	//}
 
 	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/unversioned/batch.go b/pkg/client/unversioned/batch.go
index a432e4c789c..b9f30fa8d06 100644
--- a/pkg/client/unversioned/batch.go
+++ b/pkg/client/unversioned/batch.go
@@ -73,6 +73,7 @@ func setBatchDefaults(config *restclient.Config) error {
 	//}
 
 	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/unversioned/extensions.go b/pkg/client/unversioned/extensions.go
index 5db86dbb838..c741390a462 100644
--- a/pkg/client/unversioned/extensions.go
+++ b/pkg/client/unversioned/extensions.go
@@ -127,6 +127,7 @@ func setExtensionsDefaults(config *restclient.Config) error {
 	//}
 
 	config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
+	config.NegotiatedSerializer = api.Codecs
 	if config.QPS == 0 {
 		config.QPS = 5
 	}
diff --git a/pkg/client/unversioned/helper.go b/pkg/client/unversioned/helper.go
index a81307c34c9..0f2d6694597 100644
--- a/pkg/client/unversioned/helper.go
+++ b/pkg/client/unversioned/helper.go
@@ -231,6 +231,9 @@ func SetKubernetesDefaults(config *restclient.Config) error {
 	// TODO: Unconditionally set the config.Version, until we fix the config.
 	copyGroupVersion := g.GroupVersion
 	config.GroupVersion = &copyGroupVersion
+	if config.NegotiatedSerializer == nil {
+		config.NegotiatedSerializer = api.Codecs
+	}
 	if config.Codec == nil {
 		config.Codec = api.Codecs.LegacyCodec(*config.GroupVersion)
 	}
diff --git a/pkg/client/unversioned/helper_test.go b/pkg/client/unversioned/helper_test.go
index 1d506ff9763..80660a6d056 100644
--- a/pkg/client/unversioned/helper_test.go
+++ b/pkg/client/unversioned/helper_test.go
@@ -40,8 +40,9 @@ func TestSetKubernetesDefaults(t *testing.T) {
 			restclient.Config{
 				APIPath: "/api",
 				ContentConfig: restclient.ContentConfig{
-					GroupVersion: testapi.Default.GroupVersion(),
-					Codec:        testapi.Default.Codec(),
+					GroupVersion:         testapi.Default.GroupVersion(),
+					Codec:                testapi.Default.Codec(),
+					NegotiatedSerializer: testapi.NegotiatedSerializer,
 				},
 				QPS:   5,
 				Burst: 10,
@@ -125,7 +126,7 @@ func TestHelperGetServerAPIVersions(t *testing.T) {
 		w.Write(output)
 	}))
 	defer server.Close()
-	got, err := restclient.ServerAPIVersions(&restclient.Config{Host: server.URL, ContentConfig: restclient.ContentConfig{GroupVersion: &unversioned.GroupVersion{Group: "invalid version", Version: "one"}, Codec: testapi.Default.Codec()}})
+	got, err := restclient.ServerAPIVersions(&restclient.Config{Host: server.URL, ContentConfig: restclient.ContentConfig{GroupVersion: &unversioned.GroupVersion{Group: "invalid version", Version: "one"}, NegotiatedSerializer: testapi.NegotiatedSerializer}})
 	if err != nil {
 		t.Fatalf("unexpected encoding error: %v", err)
 	}
diff --git a/pkg/client/unversioned/remotecommand/remotecommand_test.go b/pkg/client/unversioned/remotecommand/remotecommand_test.go
index 84b16219d9e..5bc8b1101cc 100644
--- a/pkg/client/unversioned/remotecommand/remotecommand_test.go
+++ b/pkg/client/unversioned/remotecommand/remotecommand_test.go
@@ -212,7 +212,10 @@ func TestStream(t *testing.T) {
 			server := httptest.NewServer(fakeServer(t, name, exec, testCase.Stdin, testCase.Stdout, testCase.Stderr, testCase.Error, testCase.Tty, testCase.MessageCount, testCase.ServerProtocols))
 
 			url, _ := url.ParseRequestURI(server.URL)
-			c := restclient.NewRESTClient(url, "", restclient.ContentConfig{GroupVersion: &unversioned.GroupVersion{Group: "x"}}, -1, -1, nil, nil)
+			c, err := restclient.NewRESTClient(url, "", restclient.ContentConfig{GroupVersion: &unversioned.GroupVersion{Group: "x"}}, -1, -1, nil, nil)
+			if err != nil {
+				t.Fatalf("failed to create a client: %v", err)
+			}
 			req := c.Post().Resource("testing")
 
 			if exec {