diff --git a/DEPRECATED.md b/DEPRECATED.md
index ace294b0ff31..389c0ecd9510 100644
--- a/DEPRECATED.md
+++ b/DEPRECATED.md
@@ -17,6 +17,7 @@ A logged warning is expected for each deprecated item that is in deprecation win
   Prior to 1.8.0, Envoy can use either proto to send client requests to a ratelimit server with the use of the
   `use_data_plane_proto` boolean flag in the [ratelimit configuration](https://github.com/envoyproxy/envoy/blob/master/api/envoy/config/ratelimit/v2/rls.proto).
   However, when using the deprecated client a warning is logged.
+* Use of the --v2-config-only flag.
 
 ## Version 1.7.0
 
diff --git a/docs/root/configuration/overview/v2_overview.rst b/docs/root/configuration/overview/v2_overview.rst
index f67e2ceb4629..feb1032a4d4a 100644
--- a/docs/root/configuration/overview/v2_overview.rst
+++ b/docs/root/configuration/overview/v2_overview.rst
@@ -37,12 +37,9 @@ flag, i.e.:
 
 .. code-block:: console
 
-  ./envoy -c <path to config>.{json,yaml,pb,pb_text} --v2-config-only
+  ./envoy -c <path to config>.{json,yaml,pb,pb_text}
 
-where the extension reflects the underlying v2 config representation. The
-:option:`--v2-config-only` flag is not strictly required as Envoy will attempt
-to autodetect the config file version, but this option provides an enhanced
-debug experience when configuration parsing fails.
+where the extension reflects the underlying v2 config representation.
 
 The :ref:`Bootstrap <envoy_api_msg_config.bootstrap.v2.Bootstrap>` message is the root of the
 configuration. A key concept in the :ref:`Bootstrap <envoy_api_msg_config.bootstrap.v2.Bootstrap>`
diff --git a/docs/root/intro/version_history.rst b/docs/root/intro/version_history.rst
index 580daf97e487..68bb3340bcf0 100644
--- a/docs/root/intro/version_history.rst
+++ b/docs/root/intro/version_history.rst
@@ -7,7 +7,7 @@ Version history
   to filter based on the presence of Envoy response flags.
 * admin: added :http:get:`/hystrix_event_stream` as an endpoint for monitoring envoy's statistics
   through `Hystrix dashboard <https://github.com/Netflix-Skunkworks/hystrix-dashboard/wiki>`_.
-* config: v1 disabled by default. v1 support remains available until October via flipping --v2-config-only=false.
+* config: v1 disabled by default. v1 support remains available until October via setting :option:`--allow-deprecated-v1-api`.
 * health check: added support for :ref:`custom health check <envoy_api_field_core.HealthCheck.custom_health_check>`.
 * health check: added support for :ref:`specifying jitter as a percentage <envoy_api_field_core.HealthCheck.interval_jitter_percent>`.
 * health_check: added support for :ref:`health check event logging <arch_overview_health_check_logging>`.
diff --git a/docs/root/operations/cli.rst b/docs/root/operations/cli.rst
index e50e99462e32..c6081452c677 100644
--- a/docs/root/operations/cli.rst
+++ b/docs/root/operations/cli.rst
@@ -11,8 +11,8 @@ following are the command line options that Envoy supports.
   *(optional)* The path to the v1 or v2 :ref:`JSON/YAML/proto3 configuration
   file <config>`. If this flag is missing, :option:`--config-yaml` is required.
   This will be parsed as a :ref:`v2 bootstrap configuration file
-  <config_overview_v2_bootstrap>` and on failure, subject to
-  :option:`--v2-config-only`, will be considered as a :ref:`v1 JSON
+  <config_overview_v2_bootstrap>`. On failure, if :option:`--allow-deprecated-v1-api`,
+  is set, it will be considered as a :ref:`v1 JSON
   configuration file <config_overview_v1>`. For v2 configuration files, valid
   extensions are ``.json``, ``.yaml``, ``.pb`` and ``.pb_text``, which indicate
   JSON, YAML, `binary proto3
@@ -34,9 +34,14 @@ following are the command line options that Envoy supports.
 
 .. option:: --v2-config-only
 
+  *(deprecated)* This flag used to allow opting into only using a
+  :ref:`v2 bootstrap configuration file <config_overview_v2_bootstrap>`. This is now set by default.
+
+.. option:: --allow-deprecated-v1-api
+
   *(optional)* This flag determines whether the configuration file should only
   be parsed as a :ref:`v2 bootstrap configuration file
-  <config_overview_v2_bootstrap>`. If false (default), when a v2 bootstrap
+  <config_overview_v2_bootstrap>`. If specified when a v2 bootstrap
   config parse fails, a second attempt to parse the config as a :ref:`v1 JSON
   configuration file <config_overview_v1>` will be made.
 
diff --git a/source/server/options_impl.cc b/source/server/options_impl.cc
index 8d47f18cb9ca..e66155781545 100644
--- a/source/server/options_impl.cc
+++ b/source/server/options_impl.cc
@@ -57,7 +57,13 @@ OptionsImpl::OptionsImpl(int argc, const char* const* argv,
   TCLAP::ValueArg<std::string> config_yaml(
       "", "config-yaml", "Inline YAML configuration, merges with the contents of --config-path",
       false, "", "string", cmd);
-  TCLAP::SwitchArg v2_config_only("", "v2-config-only", "parse config as v2 only", cmd, true);
+
+  // Deprecated and unused.
+  TCLAP::SwitchArg v2_config_only("", "v2-config-only", "deprecated", cmd, true);
+
+  TCLAP::SwitchArg allow_v1_config("", "allow-deprecated-v1-api", "allow use of legacy v1 config",
+                                   cmd, false);
+
   TCLAP::ValueArg<std::string> admin_address_path("", "admin-address-path", "Admin address path",
                                                   false, "", "string", cmd);
   TCLAP::ValueArg<std::string> local_address_ip_version("", "local-address-ip-version",
@@ -177,7 +183,7 @@ OptionsImpl::OptionsImpl(int argc, const char* const* argv,
   concurrency_ = concurrency.getValue();
   config_path_ = config_path.getValue();
   config_yaml_ = config_yaml.getValue();
-  v2_config_only_ = v2_config_only.getValue();
+  v2_config_only_ = !allow_v1_config.getValue();
   admin_address_path_ = admin_address_path.getValue();
   log_path_ = log_path.getValue();
   restart_epoch_ = restart_epoch.getValue();
diff --git a/test/server/options_impl_test.cc b/test/server/options_impl_test.cc
index 9a9def19817e..c6077699e41c 100644
--- a/test/server/options_impl_test.cc
+++ b/test/server/options_impl_test.cc
@@ -60,6 +60,27 @@ TEST(OptionsImplTest, InvalidCommandLine) {
                           "Couldn't find match for argument");
 }
 
+TEST(OptionsImplTest, v1Allowed) {
+  std::unique_ptr<OptionsImpl> options = createOptionsImpl(
+      "envoy --mode validate --concurrency 2 -c hello --admin-address-path path --restart-epoch 1 "
+      "--local-address-ip-version v6 -l info --service-cluster cluster --service-node node "
+      "--service-zone zone --file-flush-interval-msec 9000 --drain-time-s 60 --log-format [%v] "
+      "--parent-shutdown-time-s 90 --log-path /foo/bar --allow-deprecated-v1-api "
+      "--disable-hot-restart");
+  EXPECT_EQ(Server::Mode::Validate, options->mode());
+  EXPECT_FALSE(options->v2ConfigOnly());
+}
+
+TEST(OptionsImplTest, v1Disallowed) {
+  std::unique_ptr<OptionsImpl> options = createOptionsImpl(
+      "envoy --mode validate --concurrency 2 -c hello --admin-address-path path --restart-epoch 1 "
+      "--local-address-ip-version v6 -l info --service-cluster cluster --service-node node "
+      "--service-zone zone --file-flush-interval-msec 9000 --drain-time-s 60 --log-format [%v] "
+      "--parent-shutdown-time-s 90 --log-path /foo/bar --disable-hot-restart");
+  EXPECT_EQ(Server::Mode::Validate, options->mode());
+  EXPECT_TRUE(options->v2ConfigOnly());
+}
+
 TEST(OptionsImplTest, All) {
   std::unique_ptr<OptionsImpl> options = createOptionsImpl(
       "envoy --mode validate --concurrency 2 -c hello --admin-address-path path --restart-epoch 1 "
@@ -69,7 +90,7 @@ TEST(OptionsImplTest, All) {
   EXPECT_EQ(Server::Mode::Validate, options->mode());
   EXPECT_EQ(2U, options->concurrency());
   EXPECT_EQ("hello", options->configPath());
-  EXPECT_FALSE(options->v2ConfigOnly());
+  EXPECT_TRUE(options->v2ConfigOnly());
   EXPECT_EQ("path", options->adminAddressPath());
   EXPECT_EQ(Network::Address::IpVersion::v6, options->localAddressIpVersion());
   EXPECT_EQ(1U, options->restartEpoch());