diff --git a/quic/core/crypto/transport_parameters.cc b/quic/core/crypto/transport_parameters.cc
index 61e8f7c..6ca4b24 100644
--- a/quic/core/crypto/transport_parameters.cc
+++ b/quic/core/crypto/transport_parameters.cc
@@ -56,7 +56,7 @@
   kGoogleConnectionOptions = 0x3128,
   kGoogleUserAgentId = 0x3129,
   // 0x312A was used only in T050 to indicate support for HANDSHAKE_DONE.
-  kGoogleKeyUpdateNotYetSupported = 0x312B,
+  // 0x312B was used to indicate that QUIC+TLS key updates were not supported.
   // 0x4751 was used for non-standard Google-specific parameters encoded as a
   // Google QUIC_CRYPTO CHLO, it has been replaced by individual parameters.
   kGoogleQuicVersion =
@@ -124,8 +124,6 @@
       return "google_connection_options";
     case TransportParameters::kGoogleUserAgentId:
       return "user_agent_id";
-    case TransportParameters::kGoogleKeyUpdateNotYetSupported:
-      return "key_update_not_yet_supported";
     case TransportParameters::kGoogleQuicVersion:
       return "google-version";
     case TransportParameters::kMinAckDelay:
@@ -166,8 +164,6 @@
       return GetQuicReloadableFlag(quic_version_information);
     case TransportParameters::kGoogleUserAgentId:
       return !GetQuicReloadableFlag(quic_ignore_user_agent_transport_parameter);
-    case TransportParameters::kGoogleKeyUpdateNotYetSupported:
-      return !GetQuicReloadableFlag(quic_ignore_key_update_not_yet_supported);
   }
   return false;
 }
@@ -451,9 +447,6 @@
     rv += " " + TransportParameterIdToString(kGoogleUserAgentId) + " \"" +
           user_agent_id.value() + "\"";
   }
-  if (key_update_not_yet_supported) {
-    rv += " " + TransportParameterIdToString(kGoogleKeyUpdateNotYetSupported);
-  }
   for (const auto& kv : custom_parameters) {
     absl::StrAppend(&rv, " 0x", absl::Hex(static_cast<uint32_t>(kv.first)),
                     "=");
@@ -493,8 +486,7 @@
                                  kMinActiveConnectionIdLimitTransportParam,
                                  kVarInt62MaxValue),
       max_datagram_frame_size(kMaxDatagramFrameSize),
-      initial_round_trip_time_us(kInitialRoundTripTime),
-      key_update_not_yet_supported(false)
+      initial_round_trip_time_us(kInitialRoundTripTime)
 // Important note: any new transport parameters must be added
 // to TransportParameters::AreValid, SerializeTransportParameters and
 // ParseTransportParameters, TransportParameters's custom copy constructor, the
@@ -529,7 +521,6 @@
       initial_round_trip_time_us(other.initial_round_trip_time_us),
       google_connection_options(other.google_connection_options),
       user_agent_id(other.user_agent_id),
-      key_update_not_yet_supported(other.key_update_not_yet_supported),
       custom_parameters(other.custom_parameters) {
   if (other.preferred_address) {
     preferred_address = std::make_unique<TransportParameters::PreferredAddress>(
@@ -571,7 +562,6 @@
             rhs.initial_round_trip_time_us.value() &&
         google_connection_options == rhs.google_connection_options &&
         user_agent_id == rhs.user_agent_id &&
-        key_update_not_yet_supported == rhs.key_update_not_yet_supported &&
         custom_parameters == rhs.custom_parameters)) {
     return false;
   }
@@ -759,7 +749,6 @@
       kIntegerParameterLength +           // initial_round_trip_time_us
       kTypeAndValueLength +               // google_connection_options
       kTypeAndValueLength +               // user_agent_id
-      kTypeAndValueLength +               // key_update_not_yet_supported
       kTypeAndValueLength;                // google-version
 
   std::vector<TransportParameters::TransportParameterId> parameter_ids = {
@@ -785,7 +774,6 @@
       TransportParameters::kRetrySourceConnectionId,
       TransportParameters::kGoogleConnectionOptions,
       TransportParameters::kGoogleUserAgentId,
-      TransportParameters::kGoogleKeyUpdateNotYetSupported,
       TransportParameters::kGoogleQuicVersion,
       TransportParameters::kVersionInformation,
   };
@@ -1136,18 +1124,6 @@
           }
         }
       } break;
-      // Google-specific indicator for key update not yet supported.
-      case TransportParameters::kGoogleKeyUpdateNotYetSupported: {
-        if (in.key_update_not_yet_supported) {
-          if (!writer.WriteVarInt62(
-                  TransportParameters::kGoogleKeyUpdateNotYetSupported) ||
-              !writer.WriteVarInt62(/* transport parameter length */ 0)) {
-            QUIC_BUG(Failed to write key_update_not_yet_supported)
-                << "Failed to write key_update_not_yet_supported for " << in;
-            return false;
-          }
-        }
-      } break;
       // Google-specific version extension.
       case TransportParameters::kGoogleQuicVersion: {
         if (!in.legacy_version_information.has_value()) {
@@ -1493,31 +1469,6 @@
         }
         out->user_agent_id = std::string(value_reader.ReadRemainingPayload());
         break;
-      case TransportParameters::kGoogleKeyUpdateNotYetSupported:
-        if (GetQuicReloadableFlag(quic_ignore_key_update_not_yet_supported)) {
-          QUIC_RELOADABLE_FLAG_COUNT_N(quic_ignore_key_update_not_yet_supported,
-                                       1, 2);
-          QUIC_CODE_COUNT(quic_ignore_key_update_not_yet_supported_ignored);
-          // This is a copy of the default switch statement below.
-          // TODO(dschinazi) remove this case entirely when deprecating the
-          // quic_ignore_key_update_not_yet_supported flag.
-          if (out->custom_parameters.find(param_id) !=
-              out->custom_parameters.end()) {
-            *error_details = "Received a second unknown parameter" +
-                             TransportParameterIdToString(param_id);
-            return false;
-          }
-          out->custom_parameters[param_id] =
-              std::string(value_reader.ReadRemainingPayload());
-          break;
-        }
-        QUIC_CODE_COUNT(quic_ignore_key_update_not_yet_supported_received);
-        if (out->key_update_not_yet_supported) {
-          *error_details = "Received a second key_update_not_yet_supported";
-          return false;
-        }
-        out->key_update_not_yet_supported = true;
-        break;
       case TransportParameters::kGoogleQuicVersion: {
         if (!out->legacy_version_information.has_value()) {
           out->legacy_version_information =
diff --git a/quic/core/crypto/transport_parameters.h b/quic/core/crypto/transport_parameters.h
index fa34935..74f05bb 100644
--- a/quic/core/crypto/transport_parameters.h
+++ b/quic/core/crypto/transport_parameters.h
@@ -263,10 +263,6 @@
   // Google-specific user agent identifier.
   absl::optional<std::string> user_agent_id;
 
-  // Google-specific mechanism to indicate that IETF QUIC Key Update has not
-  // yet been implemented. This will be removed once we implement it.
-  bool key_update_not_yet_supported;
-
   // Validates whether transport parameters are valid according to
   // the specification. If the transport parameters are not valid, this method
   // will write a human-readable error message to |error_details|.
diff --git a/quic/core/crypto/transport_parameters_test.cc b/quic/core/crypto/transport_parameters_test.cc
index d9b5573..111d43a 100644
--- a/quic/core/crypto/transport_parameters_test.cc
+++ b/quic/core/crypto/transport_parameters_test.cc
@@ -37,7 +37,6 @@
 const uint8_t kFakePreferredStatelessResetTokenData[16] = {
     0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
     0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F};
-const bool kFakeKeyUpdateNotYetSupported = true;
 
 const auto kCustomParameter1 =
     static_cast<TransportParameters::TransportParameterId>(0xffcd);
@@ -292,7 +291,6 @@
   orig_params.initial_round_trip_time_us.set_value(kFakeInitialRoundTripTime);
   orig_params.google_connection_options = CreateFakeGoogleConnectionOptions();
   orig_params.user_agent_id = CreateFakeUserAgentId();
-  orig_params.key_update_not_yet_supported = kFakeKeyUpdateNotYetSupported;
   orig_params.custom_parameters[kCustomParameter1] = kCustomParameter1Value;
   orig_params.custom_parameters[kCustomParameter2] = kCustomParameter2Value;
 
@@ -332,9 +330,6 @@
   if (!GetQuicReloadableFlag(quic_ignore_user_agent_transport_parameter)) {
     orig_params.user_agent_id = CreateFakeUserAgentId();
   }
-  if (!GetQuicReloadableFlag(quic_ignore_key_update_not_yet_supported)) {
-    orig_params.key_update_not_yet_supported = kFakeKeyUpdateNotYetSupported;
-  }
   orig_params.custom_parameters[kCustomParameter1] = kCustomParameter1Value;
   orig_params.custom_parameters[kCustomParameter2] = kCustomParameter2Value;
 
@@ -582,9 +577,6 @@
       0x71, 0x29,  // parameter id
       0x08,  // length
       'F', 'a', 'k', 'e', 'U', 'A', 'I', 'D',  // value
-      // key_update_not_yet_supported
-      0x71, 0x2B,  // parameter id
-      0x00,  // length
       // Google version extension
       0x80, 0x00, 0x47, 0x52,  // parameter id
       0x04,  // length
@@ -655,9 +647,6 @@
   } else {
     EXPECT_FALSE(new_params.user_agent_id.has_value());
   }
-  if (!GetQuicReloadableFlag(quic_ignore_key_update_not_yet_supported)) {
-    EXPECT_TRUE(new_params.key_update_not_yet_supported);
-  }
 }
 
 TEST_P(TransportParametersTest,
@@ -844,9 +833,6 @@
       'A', 'L', 'P', 'N',  // value
       'E', 'F', 'G', 0x00,
       'H', 'I', 'J', 0xff,
-      // key_update_not_yet_supported
-      0x71, 0x2B,  // parameter id
-      0x00,  // length
       // Google version extension
       0x80, 0x00, 0x47, 0x52,  // parameter id
       0x0d,  // length
@@ -934,9 +920,6 @@
   EXPECT_EQ(CreateFakeGoogleConnectionOptions(),
             new_params.google_connection_options.value());
   EXPECT_FALSE(new_params.user_agent_id.has_value());
-  if (!GetQuicReloadableFlag(quic_ignore_key_update_not_yet_supported)) {
-    EXPECT_TRUE(new_params.key_update_not_yet_supported);
-  }
 }
 
 TEST_P(TransportParametersTest, ParseServerParametersRepeated) {
@@ -1055,7 +1038,6 @@
   orig_params.initial_round_trip_time_us.set_value(kFakeInitialRoundTripTime);
   orig_params.google_connection_options = CreateFakeGoogleConnectionOptions();
   orig_params.user_agent_id = CreateFakeUserAgentId();
-  orig_params.key_update_not_yet_supported = kFakeKeyUpdateNotYetSupported;
   orig_params.custom_parameters[kCustomParameter1] = kCustomParameter1Value;
   orig_params.custom_parameters[kCustomParameter2] = kCustomParameter2Value;
 
diff --git a/quic/core/http/quic_spdy_session_test.cc b/quic/core/http/quic_spdy_session_test.cc
index 5db1aab..4550621 100644
--- a/quic/core/http/quic_spdy_session_test.cc
+++ b/quic/core/http/quic_spdy_session_test.cc
@@ -153,7 +153,6 @@
   }
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> /*application_state*/) override {}
-  bool KeyUpdateSupportedLocally() const override { return false; }
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override {
     return nullptr;
diff --git a/quic/core/http/quic_spdy_stream_test.cc b/quic/core/http/quic_spdy_stream_test.cc
index 3bbb271..c8146e1 100644
--- a/quic/core/http/quic_spdy_stream_test.cc
+++ b/quic/core/http/quic_spdy_stream_test.cc
@@ -136,7 +136,6 @@
   }
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> /*application_state*/) override {}
-  bool KeyUpdateSupportedLocally() const override { return true; }
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override {
     return nullptr;
diff --git a/quic/core/quic_config.cc b/quic/core/quic_config.cc
index 796c641..8313ef7 100644
--- a/quic/core/quic_config.cc
+++ b/quic/core/quic_config.cc
@@ -456,8 +456,6 @@
       initial_stream_flow_control_window_bytes_(kSFCW, PRESENCE_OPTIONAL),
       initial_session_flow_control_window_bytes_(kCFCW, PRESENCE_OPTIONAL),
       connection_migration_disabled_(kNCMR, PRESENCE_OPTIONAL),
-      key_update_supported_remotely_(false),
-      key_update_supported_locally_(false),
       alternate_server_address_ipv6_(kASAD, PRESENCE_OPTIONAL),
       alternate_server_address_ipv4_(kASAD, PRESENCE_OPTIONAL),
       stateless_reset_token_(kSRST, PRESENCE_OPTIONAL),
@@ -863,22 +861,6 @@
   return connection_migration_disabled_.HasReceivedValue();
 }
 
-void QuicConfig::SetKeyUpdateSupportedLocally() {
-  key_update_supported_locally_ = true;
-}
-
-bool QuicConfig::KeyUpdateSupportedForConnection() const {
-  return KeyUpdateSupportedRemotely() && KeyUpdateSupportedLocally();
-}
-
-bool QuicConfig::KeyUpdateSupportedLocally() const {
-  return key_update_supported_locally_;
-}
-
-bool QuicConfig::KeyUpdateSupportedRemotely() const {
-  return key_update_supported_remotely_;
-}
-
 void QuicConfig::SetIPv6AlternateServerAddressToSend(
     const QuicSocketAddress& alternate_server_address_ipv6) {
   if (!alternate_server_address_ipv6.host().IsIPv6()) {
@@ -1297,10 +1279,6 @@
     params->google_connection_options = connection_options_.GetSendValues();
   }
 
-  if (!KeyUpdateSupportedLocally()) {
-    params->key_update_not_yet_supported = true;
-  }
-
   params->custom_parameters = custom_transport_parameters_to_send_;
 
   return true;
@@ -1410,9 +1388,6 @@
   if (params.disable_active_migration) {
     connection_migration_disabled_.SetReceivedValue(1u);
   }
-  if (!is_resumption && !params.key_update_not_yet_supported) {
-    key_update_supported_remotely_ = true;
-  }
 
   active_connection_id_limit_.SetReceivedValue(
       params.active_connection_id_limit.value());
diff --git a/quic/core/quic_config.h b/quic/core/quic_config.h
index cb681c2..cb8b4ec 100644
--- a/quic/core/quic_config.h
+++ b/quic/core/quic_config.h
@@ -384,12 +384,6 @@
   void SetDisableConnectionMigration();
   bool DisableConnectionMigration() const;
 
-  // Key update support.
-  void SetKeyUpdateSupportedLocally();
-  bool KeyUpdateSupportedForConnection() const;
-  bool KeyUpdateSupportedLocally() const;
-  bool KeyUpdateSupportedRemotely() const;
-
   // IPv6 alternate server address.
   void SetIPv6AlternateServerAddressToSend(
       const QuicSocketAddress& alternate_server_address_ipv6);
@@ -593,13 +587,6 @@
   // Uses the disable_active_migration transport parameter in IETF QUIC.
   QuicFixedUint32 connection_migration_disabled_;
 
-  // Whether key update is supported by the peer. Uses key_update_not_yet
-  // supported transport parameter in IETF QUIC.
-  bool key_update_supported_remotely_;
-
-  // Whether key update is supported locally.
-  bool key_update_supported_locally_;
-
   // Alternate server addresses the client could connect to.
   // Uses the preferred_address transport parameter in IETF QUIC.
   // Note that when QUIC_CRYPTO is in use, only one of the addresses is sent.
diff --git a/quic/core/quic_config_test.cc b/quic/core/quic_config_test.cc
index 5124a97..e53d429 100644
--- a/quic/core/quic_config_test.cc
+++ b/quic/core/quic_config_test.cc
@@ -56,9 +56,6 @@
   EXPECT_FALSE(config_.HasReceivedInitialMaxStreamDataBytesUnidirectional());
   EXPECT_EQ(kMaxIncomingPacketSize, config_.GetMaxPacketSizeToSend());
   EXPECT_FALSE(config_.HasReceivedMaxPacketSize());
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_FALSE(config_.KeyUpdateSupportedLocally());
-  EXPECT_FALSE(config_.KeyUpdateSupportedRemotely());
 }
 
 TEST_P(QuicConfigTest, AutoSetIetfFlowControl) {
@@ -519,7 +516,6 @@
   EXPECT_EQ(
       static_cast<uint64_t>(kDefaultMinAckDelayTimeMs) * kNumMicrosPerMilli,
       params.min_ack_delay_us.value());
-  EXPECT_TRUE(params.key_update_not_yet_supported);
 
   EXPECT_EQ(params.preferred_address->ipv4_socket_address, kTestServerAddress);
   EXPECT_EQ(*reinterpret_cast<StatelessResetToken*>(
@@ -685,83 +681,6 @@
   EXPECT_TRUE(config_.DisableConnectionMigration());
 }
 
-TEST_P(QuicConfigTest, KeyUpdateNotYetSupportedTransportParameterNorLocally) {
-  if (!version_.UsesTls()) {
-    // TransportParameters are only used for QUIC+TLS.
-    return;
-  }
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_FALSE(config_.KeyUpdateSupportedLocally());
-  EXPECT_FALSE(config_.KeyUpdateSupportedRemotely());
-  TransportParameters params;
-  params.key_update_not_yet_supported = true;
-  std::string error_details;
-  EXPECT_THAT(config_.ProcessTransportParameters(
-                  params, /* is_resumption = */ false, &error_details),
-              IsQuicNoError());
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_FALSE(config_.KeyUpdateSupportedLocally());
-  EXPECT_FALSE(config_.KeyUpdateSupportedRemotely());
-}
-
-TEST_P(QuicConfigTest, KeyUpdateNotYetSupportedTransportParameter) {
-  if (!version_.UsesTls()) {
-    // TransportParameters are only used for QUIC+TLS.
-    return;
-  }
-  config_.SetKeyUpdateSupportedLocally();
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_TRUE(config_.KeyUpdateSupportedLocally());
-
-  TransportParameters params;
-  params.key_update_not_yet_supported = true;
-  std::string error_details;
-  EXPECT_THAT(config_.ProcessTransportParameters(
-                  params, /* is_resumption = */ false, &error_details),
-              IsQuicNoError());
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_TRUE(config_.KeyUpdateSupportedLocally());
-}
-
-TEST_P(QuicConfigTest, KeyUpdateSupportedRemotelyButNotLocally) {
-  if (!version_.UsesTls()) {
-    // TransportParameters are only used for QUIC+TLS.
-    return;
-  }
-  EXPECT_FALSE(config_.KeyUpdateSupportedLocally());
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-
-  TransportParameters params;
-  params.key_update_not_yet_supported = false;
-  std::string error_details;
-  EXPECT_THAT(config_.ProcessTransportParameters(
-                  params, /* is_resumption = */ false, &error_details),
-              IsQuicNoError());
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_FALSE(config_.KeyUpdateSupportedLocally());
-  EXPECT_TRUE(config_.KeyUpdateSupportedRemotely());
-}
-
-TEST_P(QuicConfigTest, KeyUpdateSupported) {
-  if (!version_.UsesTls()) {
-    // TransportParameters are only used for QUIC+TLS.
-    return;
-  }
-  config_.SetKeyUpdateSupportedLocally();
-  EXPECT_TRUE(config_.KeyUpdateSupportedLocally());
-  EXPECT_FALSE(config_.KeyUpdateSupportedForConnection());
-
-  TransportParameters params;
-  params.key_update_not_yet_supported = false;
-  std::string error_details;
-  EXPECT_THAT(config_.ProcessTransportParameters(
-                  params, /* is_resumption = */ false, &error_details),
-              IsQuicNoError());
-  EXPECT_TRUE(config_.KeyUpdateSupportedForConnection());
-  EXPECT_TRUE(config_.KeyUpdateSupportedLocally());
-  EXPECT_TRUE(config_.KeyUpdateSupportedRemotely());
-}
-
 TEST_P(QuicConfigTest, SendPreferredIPv4Address) {
   if (!version_.UsesTls()) {
     // TransportParameters are only used for QUIC+TLS.
diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 1c1a4ea..974e192 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -505,8 +505,7 @@
     if (!ValidateConfigConnectionIds(config)) {
       return;
     }
-    support_key_update_for_connection_ =
-        config.KeyUpdateSupportedForConnection();
+    support_key_update_for_connection_ = version().UsesTls();
     framer_.SetKeyUpdateSupportForConnection(
         support_key_update_for_connection_);
   } else {
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 053849f..0969070 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -12758,13 +12758,11 @@
   }
 
   TransportParameters params;
-  params.key_update_not_yet_supported = false;
   QuicConfig config;
   std::string error_details;
   EXPECT_THAT(config.ProcessTransportParameters(
                   params, /* is_resumption = */ false, &error_details),
               IsQuicNoError());
-  config.SetKeyUpdateSupportedLocally();
   QuicConfigPeer::SetNegotiated(&config, true);
   if (connection_.version().UsesTls()) {
     QuicConfigPeer::SetReceivedOriginalConnectionId(
@@ -12920,12 +12918,10 @@
   std::string error_details;
   TransportParameters params;
   // Key update is enabled.
-  params.key_update_not_yet_supported = false;
   QuicConfig config;
   EXPECT_THAT(config.ProcessTransportParameters(
                   params, /* is_resumption = */ false, &error_details),
               IsQuicNoError());
-  config.SetKeyUpdateSupportedLocally();
   QuicConfigPeer::SetNegotiated(&config, true);
   if (connection_.version().UsesTls()) {
     QuicConfigPeer::SetReceivedOriginalConnectionId(
@@ -13018,12 +13014,10 @@
   std::string error_details;
   TransportParameters params;
   // Key update is enabled.
-  params.key_update_not_yet_supported = false;
   QuicConfig config;
   EXPECT_THAT(config.ProcessTransportParameters(
                   params, /* is_resumption = */ false, &error_details),
               IsQuicNoError());
-  config.SetKeyUpdateSupportedLocally();
   QuicConfigPeer::SetNegotiated(&config, true);
   if (connection_.version().UsesTls()) {
     QuicConfigPeer::SetReceivedOriginalConnectionId(
@@ -13059,137 +13053,6 @@
   TestConnectionCloseQuicErrorCode(QUIC_AEAD_LIMIT_REACHED);
 }
 
-TEST_P(QuicConnectionTest,
-       CloseConnectionOnConfidentialityLimitKeyUpdateNotSupportedByPeer) {
-  if (!connection_.version().UsesTls()) {
-    return;
-  }
-
-  // Set key update confidentiality limit to 1 packet.
-  SetQuicFlag(FLAGS_quic_key_update_confidentiality_limit, 1U);
-  // Use confidentiality limit for connection close of 3 packets.
-  constexpr size_t kConfidentialityLimit = 3U;
-
-  std::string error_details;
-  TransportParameters params;
-  // Key update not enabled for this connection as peer doesn't support it.
-  params.key_update_not_yet_supported = true;
-  QuicConfig config;
-  EXPECT_THAT(config.ProcessTransportParameters(
-                  params, /* is_resumption = */ false, &error_details),
-              IsQuicNoError());
-  // Key update is supported locally.
-  config.SetKeyUpdateSupportedLocally();
-  QuicConfigPeer::SetNegotiated(&config, true);
-  if (connection_.version().UsesTls()) {
-    QuicConfigPeer::SetReceivedOriginalConnectionId(
-        &config, connection_.connection_id());
-    QuicConfigPeer::SetReceivedInitialSourceConnectionId(
-        &config, connection_.connection_id());
-  }
-  EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
-  connection_.SetFromConfig(config);
-
-  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
-  connection_.SetEncrypter(
-      ENCRYPTION_FORWARD_SECURE,
-      std::make_unique<NullEncrypterWithConfidentialityLimit>(
-          Perspective::IS_CLIENT, kConfidentialityLimit));
-  EXPECT_CALL(visitor_, GetHandshakeState())
-      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
-  connection_.OnHandshakeComplete();
-
-  QuicPacketNumber last_packet;
-  // Send 3 packets and receive acks for them. Since key update is not enabled
-  // the confidentiality limit should be reached, forcing the connection to be
-  // closed.
-  SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);
-  EXPECT_TRUE(connection_.connected());
-  // Receive ack for packet.
-  EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
-  QuicAckFrame frame1 = InitAckFrame(1);
-  ProcessAckPacket(&frame1);
-
-  SendStreamDataToPeer(2, "foo", 0, NO_FIN, &last_packet);
-  EXPECT_TRUE(connection_.connected());
-  // Receive ack for packet.
-  EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
-  QuicAckFrame frame2 = InitAckFrame(2);
-  ProcessAckPacket(&frame2);
-
-  EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
-  SendStreamDataToPeer(3, "foo", 0, NO_FIN, &last_packet);
-  EXPECT_FALSE(connection_.connected());
-  const QuicConnectionStats& stats = connection_.GetStats();
-  EXPECT_EQ(0U, stats.key_update_count);
-  TestConnectionCloseQuicErrorCode(QUIC_AEAD_LIMIT_REACHED);
-}
-
-TEST_P(QuicConnectionTest,
-       CloseConnectionOnConfidentialityLimitKeyUpdateNotEnabledLocally) {
-  if (!connection_.version().UsesTls()) {
-    return;
-  }
-
-  // Set key update confidentiality limit to 1 packet.
-  SetQuicFlag(FLAGS_quic_key_update_confidentiality_limit, 1U);
-  // Use confidentiality limit for connection close of 3 packets.
-  constexpr size_t kConfidentialityLimit = 3U;
-
-  std::string error_details;
-  TransportParameters params;
-  // Key update is supported by peer but not locally
-  // (config.SetKeyUpdateSupportedLocally is not called.)
-  params.key_update_not_yet_supported = false;
-  QuicConfig config;
-  EXPECT_THAT(config.ProcessTransportParameters(
-                  params, /* is_resumption = */ false, &error_details),
-              IsQuicNoError());
-  QuicConfigPeer::SetNegotiated(&config, true);
-  if (connection_.version().UsesTls()) {
-    QuicConfigPeer::SetReceivedOriginalConnectionId(
-        &config, connection_.connection_id());
-    QuicConfigPeer::SetReceivedInitialSourceConnectionId(
-        &config, connection_.connection_id());
-  }
-  EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
-  connection_.SetFromConfig(config);
-
-  connection_.SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
-  connection_.SetEncrypter(
-      ENCRYPTION_FORWARD_SECURE,
-      std::make_unique<NullEncrypterWithConfidentialityLimit>(
-          Perspective::IS_CLIENT, kConfidentialityLimit));
-  EXPECT_CALL(visitor_, GetHandshakeState())
-      .WillRepeatedly(Return(HANDSHAKE_CONFIRMED));
-  connection_.OnHandshakeComplete();
-
-  QuicPacketNumber last_packet;
-  // Send 3 packets and receive acks for them. Since key update is not enabled
-  // the confidentiality limit should be reached, forcing the connection to be
-  // closed.
-  SendStreamDataToPeer(1, "foo", 0, NO_FIN, &last_packet);
-  EXPECT_TRUE(connection_.connected());
-  // Receive ack for packet.
-  EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
-  QuicAckFrame frame1 = InitAckFrame(1);
-  ProcessAckPacket(&frame1);
-
-  SendStreamDataToPeer(2, "foo", 0, NO_FIN, &last_packet);
-  EXPECT_TRUE(connection_.connected());
-  // Receive ack for packet.
-  EXPECT_CALL(*send_algorithm_, OnCongestionEvent(true, _, _, _, _));
-  QuicAckFrame frame2 = InitAckFrame(2);
-  ProcessAckPacket(&frame2);
-
-  EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
-  SendStreamDataToPeer(3, "foo", 0, NO_FIN, &last_packet);
-  EXPECT_FALSE(connection_.connected());
-  const QuicConnectionStats& stats = connection_.GetStats();
-  EXPECT_EQ(0U, stats.key_update_count);
-  TestConnectionCloseQuicErrorCode(QUIC_AEAD_LIMIT_REACHED);
-}
-
 TEST_P(QuicConnectionTest, CloseConnectionOnIntegrityLimitDuringHandshake) {
   if (!connection_.version().UsesTls()) {
     return;
@@ -13345,13 +13208,11 @@
   constexpr QuicPacketCount kIntegrityLimit = 4;
 
   TransportParameters params;
-  params.key_update_not_yet_supported = false;
   QuicConfig config;
   std::string error_details;
   EXPECT_THAT(config.ProcessTransportParameters(
                   params, /* is_resumption = */ false, &error_details),
               IsQuicNoError());
-  config.SetKeyUpdateSupportedLocally();
   QuicConfigPeer::SetNegotiated(&config, true);
   if (connection_.version().UsesTls()) {
     QuicConfigPeer::SetReceivedOriginalConnectionId(
@@ -13796,12 +13657,10 @@
   // kept for key update, so enable key update for the test.
   std::string error_details;
   TransportParameters params;
-  params.key_update_not_yet_supported = false;
   QuicConfig config;
   EXPECT_THAT(config.ProcessTransportParameters(
                   params, /* is_resumption = */ false, &error_details),
               IsQuicNoError());
-  config.SetKeyUpdateSupportedLocally();
   QuicConfigPeer::SetNegotiated(&config, true);
   QuicConfigPeer::SetReceivedOriginalConnectionId(&config,
                                                   connection_.connection_id());
diff --git a/quic/core/quic_crypto_client_handshaker.cc b/quic/core/quic_crypto_client_handshaker.cc
index e9a9916..872b050 100644
--- a/quic/core/quic_crypto_client_handshaker.cc
+++ b/quic/core/quic_crypto_client_handshaker.cc
@@ -180,10 +180,6 @@
   return QuicCryptoHandshaker::BufferSizeLimitForLevel(level);
 }
 
-bool QuicCryptoClientHandshaker::KeyUpdateSupportedLocally() const {
-  return false;
-}
-
 std::unique_ptr<QuicDecrypter>
 QuicCryptoClientHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter() {
   // Key update is only defined in QUIC+TLS.
diff --git a/quic/core/quic_crypto_client_handshaker.h b/quic/core/quic_crypto_client_handshaker.h
index d9f1035..c0c94b9 100644
--- a/quic/core/quic_crypto_client_handshaker.h
+++ b/quic/core/quic_crypto_client_handshaker.h
@@ -51,7 +51,6 @@
   CryptoMessageParser* crypto_message_parser() override;
   HandshakeState GetHandshakeState() const override;
   size_t BufferSizeLimitForLevel(EncryptionLevel level) const override;
-  bool KeyUpdateSupportedLocally() const override;
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override;
   std::unique_ptr<QuicEncrypter> CreateCurrentOneRttEncrypter() override;
diff --git a/quic/core/quic_crypto_client_stream.cc b/quic/core/quic_crypto_client_stream.cc
index 31d96a3..27a2a46 100644
--- a/quic/core/quic_crypto_client_stream.cc
+++ b/quic/core/quic_crypto_client_stream.cc
@@ -114,10 +114,6 @@
   return handshaker_->BufferSizeLimitForLevel(level);
 }
 
-bool QuicCryptoClientStream::KeyUpdateSupportedLocally() const {
-  return handshaker_->KeyUpdateSupportedLocally();
-}
-
 std::unique_ptr<QuicDecrypter>
 QuicCryptoClientStream::AdvanceKeysAndCreateCurrentOneRttDecrypter() {
   return handshaker_->AdvanceKeysAndCreateCurrentOneRttDecrypter();
diff --git a/quic/core/quic_crypto_client_stream.h b/quic/core/quic_crypto_client_stream.h
index e37a570..34928b6 100644
--- a/quic/core/quic_crypto_client_stream.h
+++ b/quic/core/quic_crypto_client_stream.h
@@ -183,9 +183,6 @@
     // buffered at each encryption level.
     virtual size_t BufferSizeLimitForLevel(EncryptionLevel level) const = 0;
 
-    // Returns whether the implementation supports key update.
-    virtual bool KeyUpdateSupportedLocally() const = 0;
-
     // Called to generate a decrypter for the next key phase. Each call should
     // generate the key for phase n+1.
     virtual std::unique_ptr<QuicDecrypter>
@@ -283,7 +280,6 @@
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> application_state) override;
   size_t BufferSizeLimitForLevel(EncryptionLevel level) const override;
-  bool KeyUpdateSupportedLocally() const override;
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override;
   std::unique_ptr<QuicEncrypter> CreateCurrentOneRttEncrypter() override;
diff --git a/quic/core/quic_crypto_server_stream.cc b/quic/core/quic_crypto_server_stream.cc
index 28bfe4a..55b7bf1 100644
--- a/quic/core/quic_crypto_server_stream.cc
+++ b/quic/core/quic_crypto_server_stream.cc
@@ -435,10 +435,6 @@
   return QuicCryptoHandshaker::BufferSizeLimitForLevel(level);
 }
 
-bool QuicCryptoServerStream::KeyUpdateSupportedLocally() const {
-  return false;
-}
-
 std::unique_ptr<QuicDecrypter>
 QuicCryptoServerStream::AdvanceKeysAndCreateCurrentOneRttDecrypter() {
   // Key update is only defined in QUIC+TLS.
diff --git a/quic/core/quic_crypto_server_stream.h b/quic/core/quic_crypto_server_stream.h
index cf4f6e0..aca9e9a 100644
--- a/quic/core/quic_crypto_server_stream.h
+++ b/quic/core/quic_crypto_server_stream.h
@@ -66,7 +66,6 @@
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> state) override;
   size_t BufferSizeLimitForLevel(EncryptionLevel level) const override;
-  bool KeyUpdateSupportedLocally() const override;
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override;
   std::unique_ptr<QuicEncrypter> CreateCurrentOneRttEncrypter() override;
diff --git a/quic/core/quic_crypto_stream.h b/quic/core/quic_crypto_stream.h
index 08cb189..8197a5f 100644
--- a/quic/core/quic_crypto_stream.h
+++ b/quic/core/quic_crypto_stream.h
@@ -149,9 +149,6 @@
   // encryption level |level|.
   virtual size_t BufferSizeLimitForLevel(EncryptionLevel level) const;
 
-  // Returns whether the implementation supports key update.
-  virtual bool KeyUpdateSupportedLocally() const = 0;
-
   // Called to generate a decrypter for the next key phase. Each call should
   // generate the key for phase n+1.
   virtual std::unique_ptr<QuicDecrypter>
diff --git a/quic/core/quic_crypto_stream_test.cc b/quic/core/quic_crypto_stream_test.cc
index 1c18c7b..2c9ec0d 100644
--- a/quic/core/quic_crypto_stream_test.cc
+++ b/quic/core/quic_crypto_stream_test.cc
@@ -80,7 +80,6 @@
   HandshakeState GetHandshakeState() const override { return HANDSHAKE_START; }
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> /*application_state*/) override {}
-  bool KeyUpdateSupportedLocally() const override { return false; }
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override {
     return nullptr;
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 20154bd..1118e27 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -123,8 +123,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_match_ietf_reset_code, true)
 // When the flag is true, exit STARTUP after the same number of loss events as PROBE_UP.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_startup_probe_up_loss_events, true)
-// When true, QUIC server will ignore received key_update_not_yet_supported transport parameter.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_ignore_key_update_not_yet_supported, true)
 // When true, QUIC server will ignore received user agent transport parameter and rely on getting that information from HTTP headers.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_ignore_user_agent_transport_parameter, true)
 // When true, QUIC will both send and validate the version_information transport parameter.
diff --git a/quic/core/quic_session.cc b/quic/core/quic_session.cc
index 14d549a..202bff4 100644
--- a/quic/core/quic_session.cc
+++ b/quic/core/quic_session.cc
@@ -147,10 +147,6 @@
     connection_->OnSuccessfulVersionNegotiation();
   }
 
-  if (GetMutableCryptoStream()->KeyUpdateSupportedLocally()) {
-    config_.SetKeyUpdateSupportedLocally();
-  }
-
   if (QuicVersionUsesCryptoFrames(transport_version())) {
     return;
   }
diff --git a/quic/core/quic_session_test.cc b/quic/core/quic_session_test.cc
index 8d5e477..256865d 100644
--- a/quic/core/quic_session_test.cc
+++ b/quic/core/quic_session_test.cc
@@ -159,7 +159,6 @@
   }
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> /*application_state*/) override {}
-  MOCK_METHOD(bool, KeyUpdateSupportedLocally, (), (const, override));
   MOCK_METHOD(std::unique_ptr<QuicDecrypter>,
               AdvanceKeysAndCreateCurrentOneRttDecrypter,
               (),
@@ -235,8 +234,6 @@
         writev_consumes_all_data_(false),
         uses_pending_streams_(false),
         num_incoming_streams_created_(0) {
-    EXPECT_CALL(*GetMutableCryptoStream(), KeyUpdateSupportedLocally())
-        .WillRepeatedly(Return(false));
     Initialize();
     this->connection()->SetEncrypter(
         ENCRYPTION_FORWARD_SECURE,
@@ -2294,20 +2291,6 @@
   ASSERT_TRUE(session_.connection()->can_receive_ack_frequency_frame());
 }
 
-TEST_P(QuicSessionTestClient, KeyUpdateNotSupportedLocally) {
-  EXPECT_CALL(*session_.GetMutableCryptoStream(), KeyUpdateSupportedLocally())
-      .WillOnce(Return(false));
-  session_.Initialize();
-  EXPECT_FALSE(session_.config()->KeyUpdateSupportedLocally());
-}
-
-TEST_P(QuicSessionTestClient, KeyUpdateSupportedLocally) {
-  EXPECT_CALL(*session_.GetMutableCryptoStream(), KeyUpdateSupportedLocally())
-      .WillOnce(Return(true));
-  session_.Initialize();
-  EXPECT_TRUE(session_.config()->KeyUpdateSupportedLocally());
-}
-
 TEST_P(QuicSessionTestClient, FailedToCreateStreamIfTooCloseToIdleTimeout) {
   connection_->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
   EXPECT_TRUE(session_.CanOpenNextOutgoingBidirectionalStream());
diff --git a/quic/core/tls_client_handshaker.cc b/quic/core/tls_client_handshaker.cc
index c8306a8..7950a9d 100644
--- a/quic/core/tls_client_handshaker.cc
+++ b/quic/core/tls_client_handshaker.cc
@@ -395,10 +395,6 @@
   return TlsHandshaker::BufferSizeLimitForLevel(level);
 }
 
-bool TlsClientHandshaker::KeyUpdateSupportedLocally() const {
-  return true;
-}
-
 std::unique_ptr<QuicDecrypter>
 TlsClientHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter() {
   return TlsHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter();
diff --git a/quic/core/tls_client_handshaker.h b/quic/core/tls_client_handshaker.h
index 4543f9b..c7db0ed 100644
--- a/quic/core/tls_client_handshaker.h
+++ b/quic/core/tls_client_handshaker.h
@@ -61,7 +61,6 @@
   CryptoMessageParser* crypto_message_parser() override;
   HandshakeState GetHandshakeState() const override;
   size_t BufferSizeLimitForLevel(EncryptionLevel level) const override;
-  bool KeyUpdateSupportedLocally() const override;
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override;
   std::unique_ptr<QuicEncrypter> CreateCurrentOneRttEncrypter() override;
diff --git a/quic/core/tls_server_handshaker.cc b/quic/core/tls_server_handshaker.cc
index 15eed38..e94a597 100644
--- a/quic/core/tls_server_handshaker.cc
+++ b/quic/core/tls_server_handshaker.cc
@@ -419,10 +419,6 @@
   return TlsHandshaker::BufferSizeLimitForLevel(level);
 }
 
-bool TlsServerHandshaker::KeyUpdateSupportedLocally() const {
-  return true;
-}
-
 std::unique_ptr<QuicDecrypter>
 TlsServerHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter() {
   return TlsHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter();
@@ -483,24 +479,6 @@
   // Notify QuicConnectionDebugVisitor.
   session()->connection()->OnTransportParametersReceived(client_params);
 
-  if (GetQuicReloadableFlag(quic_ignore_key_update_not_yet_supported)) {
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_ignore_key_update_not_yet_supported, 2,
-                                 2);
-  } else {
-    // Chrome clients before 86.0.4233.0 did not send the
-    // key_update_not_yet_supported transport parameter, but they did send a
-    // Google-internal transport parameter with identifier 0x4751. We treat
-    // reception of 0x4751 as having received key_update_not_yet_supported to
-    // ensure we do not use key updates with those older clients.
-    // TODO(dschinazi) remove this workaround once all of our QUIC+TLS Finch
-    // experiments have a min_version greater than 86.0.4233.0.
-    if (client_params.custom_parameters.find(
-            static_cast<TransportParameters::TransportParameterId>(0x4751)) !=
-        client_params.custom_parameters.end()) {
-      client_params.key_update_not_yet_supported = true;
-    }
-  }
-
   if (client_params.legacy_version_information.has_value() &&
       CryptoUtils::ValidateClientHelloVersion(
           client_params.legacy_version_information.value().version,
diff --git a/quic/core/tls_server_handshaker.h b/quic/core/tls_server_handshaker.h
index 01cf19b..d2f37b0 100644
--- a/quic/core/tls_server_handshaker.h
+++ b/quic/core/tls_server_handshaker.h
@@ -80,7 +80,6 @@
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> state) override;
   size_t BufferSizeLimitForLevel(EncryptionLevel level) const override;
-  bool KeyUpdateSupportedLocally() const override;
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override;
   std::unique_ptr<QuicEncrypter> CreateCurrentOneRttEncrypter() override;
diff --git a/quic/test_tools/quic_test_utils.h b/quic/test_tools/quic_test_utils.h
index 44e9ca2..d8d0979 100644
--- a/quic/test_tools/quic_test_utils.h
+++ b/quic/test_tools/quic_test_utils.h
@@ -848,7 +848,6 @@
   HandshakeState GetHandshakeState() const override { return HANDSHAKE_START; }
   void SetServerApplicationStateForResumption(
       std::unique_ptr<ApplicationState> /*application_state*/) override {}
-  bool KeyUpdateSupportedLocally() const override { return false; }
   std::unique_ptr<QuicDecrypter> AdvanceKeysAndCreateCurrentOneRttDecrypter()
       override {
     return nullptr;