diff --git a/frontend_tests/node_tests/message_edit.js b/frontend_tests/node_tests/message_edit.js
index 16607df47b..b0beecea70 100644
--- a/frontend_tests/node_tests/message_edit.js
+++ b/frontend_tests/node_tests/message_edit.js
@@ -59,7 +59,7 @@ run_test("get_editability", ({override}) => {
 
     page_params.realm_allow_message_editing = true;
     // Limit of 0 means no time limit on editing messages
-    page_params.realm_message_content_edit_limit_seconds = 0;
+    page_params.realm_message_content_edit_limit_seconds = null;
     assert.equal(get_editability(message), editability_types.FULL);
 
     page_params.realm_message_content_edit_limit_seconds = 10;
@@ -88,7 +88,7 @@ run_test("get_editability", ({override}) => {
     page_params.realm_edit_topic_policy =
         settings_config.common_message_policy_values.by_everyone.code;
     page_params.realm_allow_message_editing = true;
-    page_params.realm_message_content_edit_limit_seconds = 0;
+    page_params.realm_message_content_edit_limit_seconds = null;
     page_params.realm_community_topic_editing_limit_seconds = 259200;
     page_params.is_admin = false;
     message.timestamp = current_timestamp - 60;
diff --git a/frontend_tests/node_tests/popovers.js b/frontend_tests/node_tests/popovers.js
index 823bd92a5b..a77829221d 100644
--- a/frontend_tests/node_tests/popovers.js
+++ b/frontend_tests/node_tests/popovers.js
@@ -244,7 +244,7 @@ test_ui("actions_popover", ({override, mock_template}) => {
     };
 
     override(page_params, "realm_allow_message_editing", true);
-    override(page_params, "realm_message_content_edit_limit_seconds", 0);
+    override(page_params, "realm_message_content_edit_limit_seconds", null);
     assert.equal(message_edit.get_editability(message), message_edit.editability_types.FULL);
 
     $target.closest = (sel) => {
diff --git a/static/js/message_edit.js b/static/js/message_edit.js
index dfdf734320..b1feefb173 100644
--- a/static/js/message_edit.js
+++ b/static/js/message_edit.js
@@ -127,7 +127,7 @@ export function get_editability(message, edit_limit_seconds_buffer = 0) {
     }
 
     if (
-        page_params.realm_message_content_edit_limit_seconds === 0 &&
+        page_params.realm_message_content_edit_limit_seconds === null &&
         message.sent_by_me &&
         !is_widget_message(message)
     ) {
diff --git a/static/js/settings_config.ts b/static/js/settings_config.ts
index 0c5877703e..1b2d4cbc0e 100644
--- a/static/js/settings_config.ts
+++ b/static/js/settings_config.ts
@@ -275,7 +275,7 @@ const time_limit_dropdown_values = new Map([
         "any_time",
         {
             text: $t({defaultMessage: "Any time"}),
-            seconds: 0,
+            seconds: null,
         },
     ],
     [
diff --git a/static/js/settings_org.js b/static/js/settings_org.js
index 60b08c82c3..00f2033f76 100644
--- a/static/js/settings_org.js
+++ b/static/js/settings_org.js
@@ -169,6 +169,11 @@ function get_property_value(property_name, for_realm_default_settings) {
         if (!page_params.realm_allow_message_editing) {
             return "never";
         }
+
+        if (page_params.realm_message_content_edit_limit_seconds === null) {
+            return "any_time";
+        }
+
         for (const [value, elem] of settings_config.msg_edit_limit_dropdown_values) {
             if (elem.seconds === page_params.realm_message_content_edit_limit_seconds) {
                 return value;
@@ -899,20 +904,33 @@ export function register_save_discard_widget_handlers(
         switch (subsection) {
             case "msg_editing": {
                 const edit_limit_setting_value = $("#id_realm_msg_edit_limit_setting").val();
-                if (edit_limit_setting_value === "never") {
-                    data.allow_message_editing = false;
-                } else if (edit_limit_setting_value === "custom_limit") {
-                    data.message_content_edit_limit_seconds = parse_time_limit(
-                        $("#id_realm_message_content_edit_limit_minutes"),
-                    );
-                    // Disable editing if the parsed time limit is 0 seconds
-                    data.allow_message_editing = Boolean(data.message_content_edit_limit_seconds);
-                } else {
-                    data.allow_message_editing = true;
-                    data.message_content_edit_limit_seconds =
-                        settings_config.msg_edit_limit_dropdown_values.get(
-                            edit_limit_setting_value,
-                        ).seconds;
+                switch (edit_limit_setting_value) {
+                    case "never": {
+                        data.allow_message_editing = false;
+
+                        break;
+                    }
+                    case "custom_limit": {
+                        data.message_content_edit_limit_seconds = parse_time_limit(
+                            $("#id_realm_message_content_edit_limit_minutes"),
+                        );
+                        data.allow_message_editing = true;
+
+                        break;
+                    }
+                    case "any_time": {
+                        data.allow_message_editing = true;
+                        data.message_content_edit_limit_seconds = JSON.stringify("unlimited");
+
+                        break;
+                    }
+                    default: {
+                        data.allow_message_editing = true;
+                        data.message_content_edit_limit_seconds =
+                            settings_config.msg_edit_limit_dropdown_values.get(
+                                edit_limit_setting_value,
+                            ).seconds;
+                    }
                 }
                 const delete_limit_setting_value = $("#id_realm_msg_delete_limit_setting").val();
                 switch (delete_limit_setting_value) {
diff --git a/templates/zerver/api/changelog.md b/templates/zerver/api/changelog.md
index ce1e7b522f..6a0504e704 100644
--- a/templates/zerver/api/changelog.md
+++ b/templates/zerver/api/changelog.md
@@ -20,6 +20,15 @@ format used by the Zulip server that they are interacting with.
 
 ## Changes in Zulip 6.0
 
+**Feature level 138**
+
+* [`POST /register`](/api/register-queue), [`GET
+  /events`](/api/get-events): `message_content_edit_limit_seconds`
+  now represents no limit using `null`, instead of the integer 0.
+* `PATCH /realm`: One now sets `message_content_edit_limit_seconds`
+  to no limit by passing the string `unlimited`, rather than the
+  integer 0.
+
 **Feature level 137**
 
 * [`GET /messages/{message_id}/read_receipts`](/api/get-read-receipts):
diff --git a/version.py b/version.py
index bd2d484eb1..bef5f2408d 100644
--- a/version.py
+++ b/version.py
@@ -33,7 +33,7 @@ DESKTOP_WARNING_VERSION = "5.4.3"
 # Changes should be accompanied by documentation explaining what the
 # new level means in templates/zerver/api/changelog.md, as well as
 # "**Changes**" entries in the endpoint's documentation in `zulip.yaml`.
-API_FEATURE_LEVEL = 137
+API_FEATURE_LEVEL = 138
 
 # Bump the minor PROVISION_VERSION to indicate that folks should provision
 # only when going from an old version of the code to a newer version. Bump
diff --git a/zerver/actions/message_edit.py b/zerver/actions/message_edit.py
index 73877065f6..026b030ac6 100644
--- a/zerver/actions/message_edit.py
+++ b/zerver/actions/message_edit.py
@@ -930,7 +930,7 @@ def check_update_message(
     # from (min_seconds_to_edit + seconds_left_buffer) in message_edit.js; if
     # you change this value also change those two parameters in message_edit.js.
     edit_limit_buffer = 20
-    if content is not None and user_profile.realm.message_content_edit_limit_seconds > 0:
+    if content is not None and user_profile.realm.message_content_edit_limit_seconds is not None:
         deadline_seconds = user_profile.realm.message_content_edit_limit_seconds + edit_limit_buffer
         if (timezone_now() - message.date_sent) > datetime.timedelta(seconds=deadline_seconds):
             raise JsonableError(_("The time limit for editing this message has passed"))
diff --git a/zerver/actions/realm_settings.py b/zerver/actions/realm_settings.py
index f035de6ca2..c5a97ed925 100644
--- a/zerver/actions/realm_settings.py
+++ b/zerver/actions/realm_settings.py
@@ -138,7 +138,7 @@ def do_set_realm_authentication_methods(
 def do_set_realm_message_editing(
     realm: Realm,
     allow_message_editing: bool,
-    message_content_edit_limit_seconds: int,
+    message_content_edit_limit_seconds: Optional[int],
     edit_topic_policy: int,
     *,
     acting_user: Optional[UserProfile],
diff --git a/zerver/lib/message.py b/zerver/lib/message.py
index 21b7a376f0..d8bbc10439 100644
--- a/zerver/lib/message.py
+++ b/zerver/lib/message.py
@@ -1615,14 +1615,16 @@ def wildcard_mention_allowed(sender: UserProfile, stream: Stream) -> bool:
     raise AssertionError("Invalid wildcard mention policy")
 
 
-def parse_message_content_delete_limit(
+def parse_message_content_edit_or_delete_limit(
     value: Union[int, str],
     special_values_map: Mapping[str, Optional[int]],
+    *,
+    setting_name: str,
 ) -> Optional[int]:
     if isinstance(value, str) and value in special_values_map.keys():
         return special_values_map[value]
     if isinstance(value, str) or value <= 0:
-        raise RequestVariableConversionError("message_content_delete_limit_seconds", value)
+        raise RequestVariableConversionError(setting_name, value)
     assert isinstance(value, int)
     return value
 
diff --git a/zerver/migrations/0406_alter_realm_message_content_edit_limit_seconds.py b/zerver/migrations/0406_alter_realm_message_content_edit_limit_seconds.py
new file mode 100644
index 0000000000..ac674f8e38
--- /dev/null
+++ b/zerver/migrations/0406_alter_realm_message_content_edit_limit_seconds.py
@@ -0,0 +1,57 @@
+# Generated by Django 3.2.12 on 2022-04-12 14:51
+
+from django.db import migrations, models
+from django.db.backends.postgresql.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+
+
+def make_zero_invalid_for_message_content_edit_limit(
+    apps: StateApps, schema_editor: BaseDatabaseSchemaEditor
+) -> None:
+    Realm = apps.get_model("zerver", "Realm")
+    Realm.DEFAULT_MESSAGE_CONTENT_EDIT_LIMIT_SECONDS = 600
+
+    Realm.objects.filter(allow_message_editing=True, message_content_edit_limit_seconds=0).update(
+        message_content_edit_limit_seconds=None
+    )
+
+    Realm.objects.filter(allow_message_editing=False, message_content_edit_limit_seconds=0).update(
+        message_content_edit_limit_seconds=Realm.DEFAULT_MESSAGE_CONTENT_EDIT_LIMIT_SECONDS
+    )
+
+
+def reverse_make_zero_invalid_for_message_content_edit_limit(
+    apps: StateApps, schema_editor: BaseDatabaseSchemaEditor
+) -> None:
+    Realm = apps.get_model("zerver", "Realm")
+    Realm.DEFAULT_MESSAGE_CONTENT_EDIT_LIMIT_SECONDS = 600
+
+    Realm.objects.filter(
+        allow_message_editing=True, message_content_edit_limit_seconds=None
+    ).update(message_content_edit_limit_seconds=0)
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("zerver", "0405_set_default_for_enable_read_receipts"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="realm",
+            name="message_content_edit_limit_seconds",
+            field=models.IntegerField(default=600, null=True),
+        ),
+        migrations.RunPython(
+            make_zero_invalid_for_message_content_edit_limit,
+            reverse_code=reverse_make_zero_invalid_for_message_content_edit_limit,
+            elidable=True,
+        ),
+        migrations.AlterField(
+            model_name="realm",
+            name="message_content_edit_limit_seconds",
+            field=models.PositiveIntegerField(default=600, null=True),
+        ),
+    ]
diff --git a/zerver/models.py b/zerver/models.py
index dd92bde2ed..ffff63ada3 100644
--- a/zerver/models.py
+++ b/zerver/models.py
@@ -457,7 +457,7 @@ class Realm(models.Model):
     DEFAULT_MESSAGE_CONTENT_DELETE_LIMIT_SECONDS = (
         600  # if changed, also change in admin.js, setting_org.js
     )
-    MESSAGE_CONTENT_DELETE_LIMIT_SPECIAL_VALUES_MAP = {
+    MESSAGE_CONTENT_EDIT_OR_DELETE_LIMIT_SPECIAL_VALUES_MAP = {
         "unlimited": None,
     }
     message_content_delete_limit_seconds: Optional[int] = models.PositiveIntegerField(
@@ -468,8 +468,8 @@ class Realm(models.Model):
     DEFAULT_MESSAGE_CONTENT_EDIT_LIMIT_SECONDS = (
         600  # if changed, also change in admin.js, setting_org.js
     )
-    message_content_edit_limit_seconds: int = models.IntegerField(
-        default=DEFAULT_MESSAGE_CONTENT_EDIT_LIMIT_SECONDS,
+    message_content_edit_limit_seconds: Optional[int] = models.PositiveIntegerField(
+        default=DEFAULT_MESSAGE_CONTENT_EDIT_LIMIT_SECONDS, null=True
     )
 
     # Whether users have access to message edit history
diff --git a/zerver/openapi/zulip.yaml b/zerver/openapi/zulip.yaml
index 3c45f740bb..0678d3a8e9 100644
--- a/zerver/openapi/zulip.yaml
+++ b/zerver/openapi/zulip.yaml
@@ -3993,10 +3993,14 @@ paths:
                                         special value `0` before Zulip 5.0 (feature level 100).
                                     message_content_edit_limit_seconds:
                                       type: integer
+                                      nullable: true
                                       description: |
                                         Messages sent more than this many seconds ago cannot be edited
                                         with this organization's
                                         [message edit policy](/help/configure-message-editing-and-deletion).
+
+                                        **Changes**: No limit was represented using the
+                                        special value `0` before Zulip 6.0 (feature level 138).
                                     move_messages_between_streams_policy:
                                       type: integer
                                       description: |
@@ -4197,7 +4201,7 @@ paths:
                                   "data":
                                     {
                                       "allow_message_editing": false,
-                                      "message_content_edit_limit_seconds": 0,
+                                      "message_content_edit_limit_seconds": 600,
                                       "edit_topic_policy": 2,
                                     },
                                   "id": 0,
@@ -11555,12 +11559,19 @@ paths:
                           [calc-full-member]: /api/roles-and-permissions#determining-if-a-user-is-a-full-member
                       realm_message_content_edit_limit_seconds:
                         type: integer
+                        nullable: true
                         description: |
                           Present if `realm` is present in `fetch_event_types`.
 
                           Messages sent more than this many seconds ago cannot be edited
                           with this organization's
                           [message edit policy](/help/configure-message-editing-and-deletion).
+
+                          Will not be 0. A 'null' value means no limit: messages can be edited
+                          regardless of how long ago they were sent.
+
+                          **Changes**: No limit was represented using the
+                          special value `0` before Zulip 6.0 (feature level 138).
                       realm_community_topic_editing_limit_seconds:
                         type: integer
                         description: |
diff --git a/zerver/tests/test_message_edit.py b/zerver/tests/test_message_edit.py
index f625cce72d..20cff113e8 100644
--- a/zerver/tests/test_message_edit.py
+++ b/zerver/tests/test_message_edit.py
@@ -964,14 +964,16 @@ class EditMessageTest(EditMessageTestCase):
     def test_edit_message_content_limit(self) -> None:
         def set_message_editing_params(
             allow_message_editing: bool,
-            message_content_edit_limit_seconds: int,
+            message_content_edit_limit_seconds: Union[int, str],
             edit_topic_policy: int,
         ) -> None:
             result = self.client_patch(
                 "/json/realm",
                 {
                     "allow_message_editing": orjson.dumps(allow_message_editing).decode(),
-                    "message_content_edit_limit_seconds": message_content_edit_limit_seconds,
+                    "message_content_edit_limit_seconds": orjson.dumps(
+                        message_content_edit_limit_seconds
+                    ).decode(),
                     "edit_topic_policy": edit_topic_policy,
                 },
             )
@@ -1031,7 +1033,7 @@ class EditMessageTest(EditMessageTestCase):
         do_edit_message_assert_error(id_, "C", "The time limit for editing this message has passed")
 
         # infinite time, all edits allowed
-        set_message_editing_params(True, 0, Realm.POLICY_ADMINS_ONLY)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_ADMINS_ONLY)
         do_edit_message_assert_success(id_, "D")
 
         # without allow_message_editing, nothing is allowed
@@ -1043,7 +1045,7 @@ class EditMessageTest(EditMessageTestCase):
         do_edit_message_assert_error(
             id_, "F", "Your organization has turned off message editing", True
         )
-        set_message_editing_params(False, 0, Realm.POLICY_ADMINS_ONLY)
+        set_message_editing_params(False, "unlimited", Realm.POLICY_ADMINS_ONLY)
         do_edit_message_assert_error(
             id_, "G", "Your organization has turned off message editing", True
         )
@@ -1051,7 +1053,7 @@ class EditMessageTest(EditMessageTestCase):
     def test_edit_topic_policy(self) -> None:
         def set_message_editing_params(
             allow_message_editing: bool,
-            message_content_edit_limit_seconds: int,
+            message_content_edit_limit_seconds: Union[int, str],
             edit_topic_policy: int,
         ) -> None:
             self.login("iago")
@@ -1059,7 +1061,9 @@ class EditMessageTest(EditMessageTestCase):
                 "/json/realm",
                 {
                     "allow_message_editing": orjson.dumps(allow_message_editing).decode(),
-                    "message_content_edit_limit_seconds": message_content_edit_limit_seconds,
+                    "message_content_edit_limit_seconds": orjson.dumps(
+                        message_content_edit_limit_seconds
+                    ).decode(),
                     "edit_topic_policy": edit_topic_policy,
                 },
             )
@@ -1102,18 +1106,18 @@ class EditMessageTest(EditMessageTestCase):
         self.subscribe(polonius, "Denmark")
 
         # any user can edit the topic of a message
-        set_message_editing_params(True, 0, Realm.POLICY_EVERYONE)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_EVERYONE)
         do_edit_message_assert_success(id_, "A", "polonius")
 
         # only members can edit topic of a message
-        set_message_editing_params(True, 0, Realm.POLICY_MEMBERS_ONLY)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_MEMBERS_ONLY)
         do_edit_message_assert_error(
             id_, "B", "You don't have permission to edit this message", "polonius"
         )
         do_edit_message_assert_success(id_, "B", "cordelia")
 
         # only full members can edit topic of a message
-        set_message_editing_params(True, 0, Realm.POLICY_FULL_MEMBERS_ONLY)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_FULL_MEMBERS_ONLY)
 
         cordelia = self.example_user("cordelia")
         do_set_realm_property(cordelia.realm, "waiting_period_threshold", 10, acting_user=None)
@@ -1129,21 +1133,21 @@ class EditMessageTest(EditMessageTestCase):
         do_edit_message_assert_success(id_, "C", "cordelia")
 
         # only moderators can edit topic of a message
-        set_message_editing_params(True, 0, Realm.POLICY_MODERATORS_ONLY)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_MODERATORS_ONLY)
         do_edit_message_assert_error(
             id_, "D", "You don't have permission to edit this message", "cordelia"
         )
         do_edit_message_assert_success(id_, "D", "shiva")
 
         # only admins can edit the topics of messages
-        set_message_editing_params(True, 0, Realm.POLICY_ADMINS_ONLY)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_ADMINS_ONLY)
         do_edit_message_assert_error(
             id_, "E", "You don't have permission to edit this message", "shiva"
         )
         do_edit_message_assert_success(id_, "E", "iago")
 
         # users cannot edit topics if allow_message_editing is False
-        set_message_editing_params(False, 0, Realm.POLICY_EVERYONE)
+        set_message_editing_params(False, "unlimited", Realm.POLICY_EVERYONE)
         do_edit_message_assert_error(
             id_, "D", "Your organization has turned off message editing", "cordelia"
         )
@@ -1151,7 +1155,7 @@ class EditMessageTest(EditMessageTestCase):
         # non-admin users cannot edit topics sent > 72 hrs ago
         message.date_sent = message.date_sent - datetime.timedelta(seconds=290000)
         message.save()
-        set_message_editing_params(True, 0, Realm.POLICY_EVERYONE)
+        set_message_editing_params(True, "unlimited", Realm.POLICY_EVERYONE)
         do_edit_message_assert_success(id_, "E", "iago")
         do_edit_message_assert_success(id_, "F", "shiva")
         do_edit_message_assert_error(
diff --git a/zerver/tests/test_realm.py b/zerver/tests/test_realm.py
index f5feb895dc..70585dd2a1 100644
--- a/zerver/tests/test_realm.py
+++ b/zerver/tests/test_realm.py
@@ -1283,7 +1283,7 @@ class RealmAPITest(ZulipTestCase):
     def test_update_realm_allow_message_editing(self) -> None:
         """Tests updating the realm property 'allow_message_editing'."""
         self.set_up_db("allow_message_editing", False)
-        self.set_up_db("message_content_edit_limit_seconds", 0)
+        self.set_up_db("message_content_edit_limit_seconds", None)
         self.set_up_db("edit_topic_policy", Realm.POLICY_ADMINS_ONLY)
         realm = self.update_with_api("allow_message_editing", True)
         realm = self.update_with_api("message_content_edit_limit_seconds", 100)
@@ -1325,6 +1325,16 @@ class RealmAPITest(ZulipTestCase):
         result = self.client_patch("/json/realm", req)
         self.assert_json_error(result, "Invalid edit_topic_policy")
 
+        # Test 0 is invalid value of message_content_edit_limit_seconds
+        invalid_message_content_edit_limit_seconds_value = 0
+        req = {
+            "message_content_edit_limit_seconds": orjson.dumps(
+                invalid_message_content_edit_limit_seconds_value
+            ).decode()
+        }
+        result = self.client_patch("/json/realm", req)
+        self.assert_json_error(result, "Bad value for 'message_content_edit_limit_seconds': 0")
+
     def test_update_realm_delete_own_message_policy(self) -> None:
         """Tests updating the realm property 'delete_own_message_policy'."""
         self.set_up_db("delete_own_message_policy", Realm.POLICY_EVERYONE)
diff --git a/zerver/views/realm.py b/zerver/views/realm.py
index dd4ba3cb37..a743a5e872 100644
--- a/zerver/views/realm.py
+++ b/zerver/views/realm.py
@@ -23,7 +23,7 @@ from zerver.decorator import require_realm_admin, require_realm_owner
 from zerver.forms import check_subdomain_available as check_subdomain
 from zerver.lib.exceptions import JsonableError, OrganizationOwnerRequired
 from zerver.lib.i18n import get_available_language_codes
-from zerver.lib.message import parse_message_content_delete_limit
+from zerver.lib.message import parse_message_content_edit_or_delete_limit
 from zerver.lib.request import REQ, has_request_variables
 from zerver.lib.response import json_success
 from zerver.lib.retention import parse_message_retention_days
@@ -82,8 +82,8 @@ def update_realm(
         json_validator=check_int_in(Realm.COMMON_MESSAGE_POLICY_TYPES), default=None
     ),
     mandatory_topics: Optional[bool] = REQ(json_validator=check_bool, default=None),
-    message_content_edit_limit_seconds: Optional[int] = REQ(
-        converter=to_non_negative_int, default=None
+    message_content_edit_limit_seconds_raw: Optional[Union[int, str]] = REQ(
+        "message_content_edit_limit_seconds", json_validator=check_string_or_int, default=None
     ),
     allow_edit_history: Optional[bool] = REQ(json_validator=check_bool, default=None),
     default_language: Optional[str] = REQ(default=None),
@@ -187,9 +187,10 @@ def update_realm(
 
     message_content_delete_limit_seconds: Optional[int] = None
     if message_content_delete_limit_seconds_raw is not None:
-        message_content_delete_limit_seconds = parse_message_content_delete_limit(
+        message_content_delete_limit_seconds = parse_message_content_edit_or_delete_limit(
             message_content_delete_limit_seconds_raw,
-            Realm.MESSAGE_CONTENT_DELETE_LIMIT_SPECIAL_VALUES_MAP,
+            Realm.MESSAGE_CONTENT_EDIT_OR_DELETE_LIMIT_SPECIAL_VALUES_MAP,
+            setting_name="message_content_delete_limit_seconds",
         )
         if (
             message_content_delete_limit_seconds is None
@@ -232,18 +233,25 @@ def update_realm(
         data["authentication_methods"] = authentication_methods
     # The message_editing settings are coupled to each other, and thus don't fit
     # into the do_set_realm_property framework.
+
+    message_content_edit_limit_seconds = realm.message_content_edit_limit_seconds
+    if message_content_edit_limit_seconds_raw is not None:
+        message_content_edit_limit_seconds = parse_message_content_edit_or_delete_limit(
+            message_content_edit_limit_seconds_raw,
+            Realm.MESSAGE_CONTENT_EDIT_OR_DELETE_LIMIT_SPECIAL_VALUES_MAP,
+            setting_name="message_content_edit_limit_seconds",
+        )
+
     if (
         (allow_message_editing is not None and realm.allow_message_editing != allow_message_editing)
         or (
-            message_content_edit_limit_seconds is not None
-            and realm.message_content_edit_limit_seconds != message_content_edit_limit_seconds
+            message_content_edit_limit_seconds_raw is not None
+            and message_content_edit_limit_seconds != realm.message_content_edit_limit_seconds
         )
         or (edit_topic_policy is not None and realm.edit_topic_policy != edit_topic_policy)
     ):
         if allow_message_editing is None:
             allow_message_editing = realm.allow_message_editing
-        if message_content_edit_limit_seconds is None:
-            message_content_edit_limit_seconds = realm.message_content_edit_limit_seconds
         if edit_topic_policy is None:
             edit_topic_policy = realm.edit_topic_policy
         do_set_realm_message_editing(