diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index ba48358879..3b1986f4f7 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,16 @@
+*   Fix the `Digest::UUID.uuid_from_hash` behavior for namespace IDs that are different from the ones defined on `Digest::UUID`.
+
+    The new behavior will be enabled by setting the
+    `config.active_support.use_rfc4122_namespaced_uuids` option to `true`
+    and is the default for new apps.
+
+    The old behavior is the default for upgraded apps and will output a
+    deprecation warning every time a value that is different than one of
+    the constants defined on the `Digest::UUID` extension is used as the
+    namespace ID.
+
+    *Alex Robbin, Erich Soares Machado, Eugene Kenny*
+
 *   `ActiveSupport::Inflector::Inflections#clear(:acronyms)` is now supported,
     and `inflector.clear` / `inflector.clear(:all)` also clears acronyms.
 
diff --git a/activesupport/lib/active_support/core_ext/digest.rb b/activesupport/lib/active_support/core_ext/digest.rb
index ce1427e13a..a226bf2146 100644
--- a/activesupport/lib/active_support/core_ext/digest.rb
+++ b/activesupport/lib/active_support/core_ext/digest.rb
@@ -1,3 +1,9 @@
 # frozen_string_literal: true
 
 require "active_support/core_ext/digest/uuid"
+
+module ActiveSupport
+  class << self
+    delegate :use_rfc4122_namespaced_uuids, :use_rfc4122_namespaced_uuids=, to: :'Digest::UUID'
+  end
+end
diff --git a/activesupport/lib/active_support/core_ext/digest/uuid.rb b/activesupport/lib/active_support/core_ext/digest/uuid.rb
index 000451f1cf..3546932c4f 100644
--- a/activesupport/lib/active_support/core_ext/digest/uuid.rb
+++ b/activesupport/lib/active_support/core_ext/digest/uuid.rb
@@ -10,13 +10,15 @@ module Digest
     OID_NAMESPACE  = "k\xA7\xB8\x12\x9D\xAD\x11\xD1\x80\xB4\x00\xC0O\xD40\xC8" # :nodoc:
     X500_NAMESPACE = "k\xA7\xB8\x14\x9D\xAD\x11\xD1\x80\xB4\x00\xC0O\xD40\xC8" # :nodoc:
 
+    mattr_accessor :use_rfc4122_namespaced_uuids, instance_accessor: false, default: false
+
     # Generates a v5 non-random UUID (Universally Unique IDentifier).
     #
     # Using OpenSSL::Digest::MD5 generates version 3 UUIDs; OpenSSL::Digest::SHA1 generates version 5 UUIDs.
     # uuid_from_hash always generates the same UUID for a given name and namespace combination.
     #
     # See RFC 4122 for details of UUID at: https://www.ietf.org/rfc/rfc4122.txt
-    def self.uuid_from_hash(hash_class, uuid_namespace, name)
+    def self.uuid_from_hash(hash_class, namespace, name)
       if hash_class == Digest::MD5 || hash_class == OpenSSL::Digest::MD5
         version = 3
       elsif hash_class == Digest::SHA1 || hash_class == OpenSSL::Digest::SHA1
@@ -25,6 +27,8 @@ module Digest
         raise ArgumentError, "Expected OpenSSL::Digest::SHA1 or OpenSSL::Digest::MD5, got #{hash_class.name}."
       end
 
+      uuid_namespace = pack_uuid_namespace(namespace)
+
       hash = hash_class.new
       hash.update(uuid_namespace)
       hash.update(name)
@@ -50,5 +54,26 @@ module Digest
     def self.uuid_v4
       SecureRandom.uuid
     end
+
+    def self.pack_uuid_namespace(namespace)
+      if [DNS_NAMESPACE, OID_NAMESPACE, URL_NAMESPACE, X500_NAMESPACE].include?(namespace)
+        namespace
+      elsif use_rfc4122_namespaced_uuids == true
+        match_data = namespace.match(/\A(\h{8})-(\h{4})-(\h{4})-(\h{4})-(\h{4})(\h{8})\z/)
+
+        raise ArgumentError, "Only UUIDs are valid namespace identifiers" unless match_data.present?
+
+        match_data.captures.map { |s| s.to_i(16) }.pack("NnnnnN")
+      else
+        ActiveSupport::Deprecation.warn <<~WARNING.squish
+          Providing a namespace ID that is not one of the constants defined on Digest::UUID generates an incorrect UUID value according to RFC 4122.
+          To enable the correct behavior, set the Rails.application.config.active_support.use_rfc4122_namespaced_uuids configuration option to true.
+        WARNING
+
+        namespace
+      end
+    end
+
+    private_class_method :pack_uuid_namespace
   end
 end
diff --git a/activesupport/lib/active_support/railtie.rb b/activesupport/lib/active_support/railtie.rb
index 8d524a2037..76ff7cd28e 100644
--- a/activesupport/lib/active_support/railtie.rb
+++ b/activesupport/lib/active_support/railtie.rb
@@ -121,5 +121,14 @@ module ActiveSupport
         end
       end
     end
+
+    initializer "active_support.set_rfc4122_namespaced_uuids" do |app|
+      config.after_initialize do
+        if app.config.active_support.use_rfc4122_namespaced_uuids
+          require "active_support/core_ext/digest"
+          ActiveSupport.use_rfc4122_namespaced_uuids = app.config.active_support.use_rfc4122_namespaced_uuids
+        end
+      end
+    end
   end
 end
diff --git a/activesupport/test/core_ext/digest/uuid_test.rb b/activesupport/test/core_ext/digest/uuid_test.rb
index 1dc21bb2dc..8749b30f42 100644
--- a/activesupport/test/core_ext/digest/uuid_test.rb
+++ b/activesupport/test/core_ext/digest/uuid_test.rb
@@ -1,21 +1,182 @@
 # frozen_string_literal: true
 
 require_relative "../../abstract_unit"
-require "active_support/core_ext/digest/uuid"
+require "active_support/core_ext/digest"
 
 class DigestUUIDExt < ActiveSupport::TestCase
-  def test_v3_uuids
-    assert_equal "3d813cbb-47fb-32ba-91df-831e1593ac29", Digest::UUID.uuid_v3(Digest::UUID::DNS_NAMESPACE, "www.widgets.com")
-    assert_equal "86df55fb-428e-3843-8583-ba3c05f290bc", Digest::UUID.uuid_v3(Digest::UUID::URL_NAMESPACE, "http://www.widgets.com")
-    assert_equal "8c29ab0e-a2dc-3482-b5eb-20cb2e2387a1", Digest::UUID.uuid_v3(Digest::UUID::OID_NAMESPACE, "1.2.3")
-    assert_equal "ee49149d-53a4-304a-890b-468229f6afc3", Digest::UUID.uuid_v3(Digest::UUID::X500_NAMESPACE, "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+  def with_use_rfc4122_namespaced_uuids_set
+    old_value = ActiveSupport.use_rfc4122_namespaced_uuids
+    ActiveSupport.use_rfc4122_namespaced_uuids = true
+    yield
+  ensure
+    ActiveSupport.use_rfc4122_namespaced_uuids = old_value
   end
 
-  def test_v5_uuids
-    assert_equal "21f7f8de-8051-5b89-8680-0195ef798b6a", Digest::UUID.uuid_v5(Digest::UUID::DNS_NAMESPACE, "www.widgets.com")
-    assert_equal "4e570fd8-186d-5a74-90f0-4d28e34673a1", Digest::UUID.uuid_v5(Digest::UUID::URL_NAMESPACE, "http://www.widgets.com")
-    assert_equal "42d5e23b-3a02-5135-85c6-52d1102f1f00", Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, "1.2.3")
-    assert_equal "fd5b2ddf-bcfe-58b6-90d6-db50f74db527", Digest::UUID.uuid_v5(Digest::UUID::X500_NAMESPACE, "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+  def test_constants
+    assert_equal "6ba7b810-9dad-11d1-80b4-00c04fd430c8", "%08x-%04x-%04x-%04x-%04x%08x" % Digest::UUID::DNS_NAMESPACE.unpack("NnnnnN")
+    assert_equal "6ba7b811-9dad-11d1-80b4-00c04fd430c8", "%08x-%04x-%04x-%04x-%04x%08x" % Digest::UUID::URL_NAMESPACE.unpack("NnnnnN")
+    assert_equal "6ba7b812-9dad-11d1-80b4-00c04fd430c8", "%08x-%04x-%04x-%04x-%04x%08x" % Digest::UUID::OID_NAMESPACE.unpack("NnnnnN")
+    assert_equal "6ba7b814-9dad-11d1-80b4-00c04fd430c8", "%08x-%04x-%04x-%04x-%04x%08x" % Digest::UUID::X500_NAMESPACE.unpack("NnnnnN")
+  end
+
+  def test_v3_uuids_with_rfc4122_namespaced_uuids_enabled
+    with_use_rfc4122_namespaced_uuids_set do
+      assert_not_deprecated do
+        assert_equal "3d813cbb-47fb-32ba-91df-831e1593ac29", Digest::UUID.uuid_v3("6BA7B810-9DAD-11D1-80B4-00C04FD430C8", "www.widgets.com")
+        assert_equal "3d813cbb-47fb-32ba-91df-831e1593ac29", Digest::UUID.uuid_v3("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.widgets.com")
+        assert_equal "3d813cbb-47fb-32ba-91df-831e1593ac29", Digest::UUID.uuid_v3(Digest::UUID::DNS_NAMESPACE, "www.widgets.com")
+
+        assert_equal "86df55fb-428e-3843-8583-ba3c05f290bc", Digest::UUID.uuid_v3("6BA7B811-9DAD-11D1-80B4-00C04FD430C8", "http://www.widgets.com")
+        assert_equal "86df55fb-428e-3843-8583-ba3c05f290bc", Digest::UUID.uuid_v3("6ba7b811-9dad-11d1-80b4-00c04fd430c8", "http://www.widgets.com")
+        assert_equal "86df55fb-428e-3843-8583-ba3c05f290bc", Digest::UUID.uuid_v3(Digest::UUID::URL_NAMESPACE, "http://www.widgets.com")
+
+        assert_equal "8c29ab0e-a2dc-3482-b5eb-20cb2e2387a1", Digest::UUID.uuid_v3("6BA7B812-9DAD-11D1-80B4-00C04FD430C8", "1.2.3")
+        assert_equal "8c29ab0e-a2dc-3482-b5eb-20cb2e2387a1", Digest::UUID.uuid_v3("6ba7b812-9dad-11d1-80b4-00c04fd430c8", "1.2.3")
+        assert_equal "8c29ab0e-a2dc-3482-b5eb-20cb2e2387a1", Digest::UUID.uuid_v3(Digest::UUID::OID_NAMESPACE, "1.2.3")
+
+        assert_equal "ee49149d-53a4-304a-890b-468229f6afc3", Digest::UUID.uuid_v3("6BA7B814-9DAD-11D1-80B4-00C04FD430C8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+        assert_equal "ee49149d-53a4-304a-890b-468229f6afc3", Digest::UUID.uuid_v3("6ba7b814-9dad-11d1-80b4-00c04fd430c8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+        assert_equal "ee49149d-53a4-304a-890b-468229f6afc3", Digest::UUID.uuid_v3(Digest::UUID::X500_NAMESPACE, "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+      end
+
+      assert_raise ArgumentError do
+        Digest::UUID.uuid_v3("A non-UUID string", "some value")
+      end
+    end
+  end
+
+  def test_v3_uuids_with_rfc4122_namespaced_uuids_disabled
+    assert_deprecated do
+      assert_equal "995e5d8e-364a-386e-8b3d-65d6a7d5478f", Digest::UUID.uuid_v3("6BA7B810-9DAD-11D1-80B4-00C04FD430C8", "www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "fe5a52d1-703f-3326-b919-2d96003288f3", Digest::UUID.uuid_v3("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.widgets.com")
+    end
+
+    assert_not_deprecated do
+      assert_equal "3d813cbb-47fb-32ba-91df-831e1593ac29", Digest::UUID.uuid_v3(Digest::UUID::DNS_NAMESPACE, "www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "1a27509f-2955-3d78-8f53-c92935fecc57", Digest::UUID.uuid_v3("6BA7B811-9DAD-11D1-80B4-00C04FD430C8", "http://www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "2676127a-9073-36e3-b9db-14bc16b7c083", Digest::UUID.uuid_v3("6ba7b811-9dad-11d1-80b4-00c04fd430c8", "http://www.widgets.com")
+    end
+
+    assert_not_deprecated do
+      assert_equal "86df55fb-428e-3843-8583-ba3c05f290bc", Digest::UUID.uuid_v3(Digest::UUID::URL_NAMESPACE, "http://www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "2e2a2437-160c-36e7-952d-d6f494edea44", Digest::UUID.uuid_v3("6BA7B812-9DAD-11D1-80B4-00C04FD430C8", "1.2.3")
+    end
+
+    assert_deprecated do
+      assert_equal "719357e1-54f1-3930-8113-a1faffde48fa", Digest::UUID.uuid_v3("6ba7b812-9dad-11d1-80b4-00c04fd430c8", "1.2.3")
+    end
+
+    assert_not_deprecated do
+      assert_equal "8c29ab0e-a2dc-3482-b5eb-20cb2e2387a1", Digest::UUID.uuid_v3(Digest::UUID::OID_NAMESPACE, "1.2.3")
+    end
+
+    assert_deprecated do
+      assert_equal "01c2671b-fd20-3e43-8cff-217f40e110c8", Digest::UUID.uuid_v3("6BA7B814-9DAD-11D1-80B4-00C04FD430C8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+    end
+
+    assert_deprecated do
+      assert_equal "32560c4a-c9f1-3974-9c1c-5e52761e091f", Digest::UUID.uuid_v3("6ba7b814-9dad-11d1-80b4-00c04fd430c8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+    end
+
+    assert_not_deprecated do
+      assert_equal "ee49149d-53a4-304a-890b-468229f6afc3", Digest::UUID.uuid_v3(Digest::UUID::X500_NAMESPACE, "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+    end
+
+    assert_deprecated do
+      assert_equal "cd3d768f-7380-3d1f-8834-e034b40e65ea", Digest::UUID.uuid_v3("A non-UUID string", "some value")
+    end
+  end
+
+  def test_v5_uuids_with_rfc4122_namespaced_uuids_enabled
+    with_use_rfc4122_namespaced_uuids_set do
+      assert_not_deprecated do
+        assert_equal "21f7f8de-8051-5b89-8680-0195ef798b6a", Digest::UUID.uuid_v5("6BA7B810-9DAD-11D1-80B4-00C04FD430C8", "www.widgets.com")
+        assert_equal "21f7f8de-8051-5b89-8680-0195ef798b6a", Digest::UUID.uuid_v5("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.widgets.com")
+        assert_equal "21f7f8de-8051-5b89-8680-0195ef798b6a", Digest::UUID.uuid_v5(Digest::UUID::DNS_NAMESPACE, "www.widgets.com")
+
+        assert_equal "4e570fd8-186d-5a74-90f0-4d28e34673a1", Digest::UUID.uuid_v5("6BA7B811-9DAD-11D1-80B4-00C04FD430C8", "http://www.widgets.com")
+        assert_equal "4e570fd8-186d-5a74-90f0-4d28e34673a1", Digest::UUID.uuid_v5("6ba7b811-9dad-11d1-80b4-00c04fd430c8", "http://www.widgets.com")
+        assert_equal "4e570fd8-186d-5a74-90f0-4d28e34673a1", Digest::UUID.uuid_v5(Digest::UUID::URL_NAMESPACE, "http://www.widgets.com")
+
+        assert_equal "42d5e23b-3a02-5135-85c6-52d1102f1f00", Digest::UUID.uuid_v5("6BA7B812-9DAD-11D1-80B4-00C04FD430C8", "1.2.3")
+        assert_equal "42d5e23b-3a02-5135-85c6-52d1102f1f00", Digest::UUID.uuid_v5("6ba7b812-9dad-11d1-80b4-00c04fd430c8", "1.2.3")
+        assert_equal "42d5e23b-3a02-5135-85c6-52d1102f1f00", Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, "1.2.3")
+
+        assert_equal "fd5b2ddf-bcfe-58b6-90d6-db50f74db527", Digest::UUID.uuid_v5("6BA7B814-9DAD-11D1-80B4-00C04FD430C8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+        assert_equal "fd5b2ddf-bcfe-58b6-90d6-db50f74db527", Digest::UUID.uuid_v5("6ba7b814-9dad-11d1-80b4-00c04fd430c8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+        assert_equal "fd5b2ddf-bcfe-58b6-90d6-db50f74db527", Digest::UUID.uuid_v5(Digest::UUID::X500_NAMESPACE, "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+      end
+
+      assert_raise ArgumentError do
+        Digest::UUID.uuid_v5("A non-UUID string", "some value")
+      end
+    end
+  end
+
+  def test_v5_uuids_with_rfc4122_namespaced_uuids_disabled
+    assert_deprecated do
+      assert_equal "442faf6c-4996-5266-aeef-ecadb5d49e54", Digest::UUID.uuid_v5("6BA7B810-9DAD-11D1-80B4-00C04FD430C8", "www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "027963ef-431c-5670-ab2c-820168da74e9", Digest::UUID.uuid_v5("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.widgets.com")
+    end
+
+    assert_not_deprecated do
+      assert_equal "21f7f8de-8051-5b89-8680-0195ef798b6a", Digest::UUID.uuid_v5(Digest::UUID::DNS_NAMESPACE, "www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "59207e54-33c5-5914-ab39-b7f3333a0097", Digest::UUID.uuid_v5("6BA7B811-9DAD-11D1-80B4-00C04FD430C8", "http://www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "d8e1e518-2337-58e5-bf52-6c563631db90", Digest::UUID.uuid_v5("6ba7b811-9dad-11d1-80b4-00c04fd430c8", "http://www.widgets.com")
+    end
+
+    assert_not_deprecated do
+      assert_equal "4e570fd8-186d-5a74-90f0-4d28e34673a1", Digest::UUID.uuid_v5(Digest::UUID::URL_NAMESPACE, "http://www.widgets.com")
+    end
+
+    assert_deprecated do
+      assert_equal "72409eff-7406-5906-b86e-6c7a726ed04e", Digest::UUID.uuid_v5("6BA7B812-9DAD-11D1-80B4-00C04FD430C8", "1.2.3")
+    end
+
+    assert_deprecated do
+      assert_equal "b9b86653-48bb-5059-861a-2c72974b5c8d", Digest::UUID.uuid_v5("6ba7b812-9dad-11d1-80b4-00c04fd430c8", "1.2.3")
+    end
+
+    assert_not_deprecated do
+      assert_equal "42d5e23b-3a02-5135-85c6-52d1102f1f00", Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, "1.2.3")
+    end
+
+    assert_deprecated do
+      assert_equal "de6fe50e-eded-580a-81c9-f0774a3531da", Digest::UUID.uuid_v5("6BA7B814-9DAD-11D1-80B4-00C04FD430C8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+    end
+
+    assert_deprecated do
+      assert_equal "e84a8a4e-a5c7-55b8-ad09-020c0b5662a7", Digest::UUID.uuid_v5("6ba7b814-9dad-11d1-80b4-00c04fd430c8", "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+    end
+
+    assert_not_deprecated do
+      assert_equal "fd5b2ddf-bcfe-58b6-90d6-db50f74db527", Digest::UUID.uuid_v5(Digest::UUID::X500_NAMESPACE, "cn=John Doe, ou=People, o=Acme, Inc., c=US")
+    end
+
+    assert_deprecated do
+      assert_equal "b42d5423-1047-5bb3-afd4-0dec60fb22d2", Digest::UUID.uuid_v5("A non-UUID string", "some value")
+    end
   end
 
   def test_invalid_hash_class
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 3ec05a292e..e484407614 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -1385,6 +1385,26 @@ Configures deprecation warnings that the Application considers disallowed. This
 
 Allows you to disable all deprecation warnings (including disallowed deprecations); it makes `ActiveSupport::Deprecation.warn` a no-op. This is enabled by default in production.
 
+#### `config.active_support.use_rfc4122_namespaced_uuids`
+
+Specifies whether generated namespaced UUIDs follow the RFC 4122 standard for namespace IDs provided as a `String` to `Digest::UUID.uuid_v3` or `Digest::UUID.uuid_v5` method calls.
+
+If set to `true`:
+
+* Only UUIDs are allowed as namespace IDs. If a namespace ID value provided is not allowed, an `ArgumentError` will be raised.
+* No deprecation warning will be generated, no matter if the namespace ID used is one of the constants defined on `Digest::UUID` or a `String`.
+* Namespace IDs are case-insensitive.
+* All generated namespaced UUIDs should be compliant to the standard.
+
+If set to `false`:
+
+* Any `String` value can be used as namespace ID (although not recommended). No `ArgumentError` will be raised in this case in order to preserve backwards-compatibility.
+* A deprecation warning will be generated if the namespace ID provided is not one of the constants defined on `Digest::UUID`.
+* Namespace IDs are case-sensitive.
+* Only namespaced UUIDs generated using one of the namespace ID constants defined on `Digest::UUID` are compliant to the standard.
+
+The default value is `true` for new apps. Upgraded apps will have that value set to `false` for backwards-compatibility.
+
 #### `ActiveSupport::Logger.silencer`
 
 Is set to `false` to disable the ability to silence logging in a block. The default is `true`.
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 99472cf410..4d4ac85516 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -213,6 +213,7 @@ module Rails
             active_support.key_generator_hash_digest_class = OpenSSL::Digest::SHA256
             active_support.remove_deprecated_time_with_zone_name = true
             active_support.cache_format_version = 7.0
+            active_support.use_rfc4122_namespaced_uuids = true
           end
 
           if respond_to?(:action_mailer)
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index eba2ad69d3..159b71f779 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -2422,6 +2422,20 @@ module ApplicationTests
       assert_equal 1234, ActiveSupport.test_parallelization_threshold
     end
 
+    test "ActiveSupport.use_rfc4122_namespaced_uuids is enabled by default for new apps" do
+      app "development"
+
+      assert_equal true, ActiveSupport.use_rfc4122_namespaced_uuids
+    end
+
+    test "ActiveSupport.use_rfc4122_namespaced_uuids is disabled by default for upgraded apps" do
+      remove_from_config '.*config\.load_defaults.*\n'
+
+      app "development"
+
+      assert_equal false, ActiveSupport.use_rfc4122_namespaced_uuids
+    end
+
     test "custom serializers should be able to set via config.active_job.custom_serializers in an initializer" do
       class ::DummySerializer < ActiveJob::Serializers::ObjectSerializer; end