diff --git a/ci/build_setup.sh b/ci/build_setup.sh
index ec5b4579799e7..dba93c0dd78d3 100755
--- a/ci/build_setup.sh
+++ b/ci/build_setup.sh
@@ -87,7 +87,7 @@ if [ "$1" != "-nofetch" ]; then
   fi
   
   # This is the hash on https://github.com/envoyproxy/envoy-filter-example.git we pin to.
-  (cd "${ENVOY_FILTER_EXAMPLE_SRCDIR}" && git fetch origin && git checkout -f 92307d723a1ead25c39f025a734fa091443efdbc)
+  (cd "${ENVOY_FILTER_EXAMPLE_SRCDIR}" && git fetch origin && git checkout -f 3e5b73305b961526ffcee7584251692a9a3ce4b3)
   cp -f "${ENVOY_SRCDIR}"/ci/WORKSPACE.filter.example "${ENVOY_FILTER_EXAMPLE_SRCDIR}"/WORKSPACE
 fi
 
diff --git a/source/common/common/assert.h b/source/common/common/assert.h
index 52e587d817f67..9d4f4c5275215 100644
--- a/source/common/common/assert.h
+++ b/source/common/common/assert.h
@@ -53,9 +53,6 @@ namespace Envoy {
 // reports.
 #define NOT_IMPLEMENTED_GCOVR_EXCL_LINE PANIC("not implemented")
 
-// Deprecated: use NOT_IMPLEMENTED_GCOVR_EXCL_LINE instead.
-#define NOT_IMPLEMENTED NOT_IMPLEMENTED_GCOVR_EXCL_LINE
-
 // NOT_REACHED_GCOVR_EXCL_LINE is for spots the compiler insists on having a return, but where we
 // know that it shouldn't be possible to arrive there, assuming no horrendous bugs. For example,
 // after a switch (some_enum) with all enum values included in the cases. The macro name includes
diff --git a/test/common/router/config_impl_test.cc b/test/common/router/config_impl_test.cc
index 5596dc2553199..e8d82f40e0aa2 100644
--- a/test/common/router/config_impl_test.cc
+++ b/test/common/router/config_impl_test.cc
@@ -4434,7 +4434,9 @@ name: NoIdleTimeout
 
 class PerFilterConfigsTest : public testing::Test {
 public:
-  PerFilterConfigsTest() : factory_(), registered_factory_(factory_) {}
+  PerFilterConfigsTest()
+      : factory_(), registered_factory_(factory_), default_factory_(),
+        registered_default_factory_(default_factory_) {}
 
   struct DerivedFilterConfig : public RouteSpecificFilterConfig {
     ProtobufWkt::Timestamp config_;
@@ -4458,6 +4460,15 @@ class PerFilterConfigsTest : public testing::Test {
       return obj;
     }
   };
+  class DefaultTestFilterConfig : public Extensions::HttpFilters::Common::EmptyHttpFilterConfig {
+  public:
+    DefaultTestFilterConfig() : EmptyHttpFilterConfig("test.default.filter") {}
+
+    Http::FilterFactoryCb createFilter(const std::string&,
+                                       Server::Configuration::FactoryContext&) override {
+      NOT_IMPLEMENTED_GCOVR_EXCL_LINE;
+    }
+  };
 
   void checkEach(const std::string& yaml, uint32_t expected_entry, uint32_t expected_route,
                  uint32_t expected_vhost) {
@@ -4481,8 +4492,24 @@ class PerFilterConfigsTest : public testing::Test {
         << "config value does not match expected for source: " << source;
   }
 
+  void checkNoPerFilterConfig(const std::string& yaml) {
+    const ConfigImpl config(parseRouteConfigurationFromV2Yaml(yaml), factory_context_, true);
+
+    const auto route = config.route(genHeaders("www.foo.com", "/", "GET"), 0);
+    const auto* route_entry = route->routeEntry();
+    const auto& vhost = route_entry->virtualHost();
+
+    EXPECT_EQ(nullptr,
+              route_entry->perFilterConfigTyped<DerivedFilterConfig>(default_factory_.name()));
+    EXPECT_EQ(nullptr, route->perFilterConfigTyped<DerivedFilterConfig>(default_factory_.name()));
+    EXPECT_EQ(nullptr, vhost.perFilterConfigTyped<DerivedFilterConfig>(default_factory_.name()));
+  }
+
   TestFilterConfig factory_;
   Registry::InjectFactory<Server::Configuration::NamedHttpFilterConfigFactory> registered_factory_;
+  DefaultTestFilterConfig default_factory_;
+  Registry::InjectFactory<Server::Configuration::NamedHttpFilterConfigFactory>
+      registered_default_factory_;
   NiceMock<Server::Configuration::MockFactoryContext> factory_context_;
 };
 
@@ -4503,6 +4530,23 @@ name: foo
       "Didn't find a registered implementation for name: 'unknown.filter'");
 }
 
+// Test that a trivially specified NamedHttpFilterConfigFactory ignores per_filter_config without
+// error.
+TEST_F(PerFilterConfigsTest, DefaultFilterImplementation) {
+  std::string yaml = R"EOF(
+name: foo
+virtual_hosts:
+  - name: bar
+    domains: ["*"]
+    routes:
+      - match: { prefix: "/" }
+        route: { cluster: baz }
+    per_filter_config: { test.default.filter: { unknown_key: 123} }
+)EOF";
+
+  checkNoPerFilterConfig(yaml);
+}
+
 TEST_F(PerFilterConfigsTest, RouteLocalConfig) {
   std::string yaml = R"EOF(
 name: foo