diff --git a/app/assets/javascripts/discourse/app/controllers/ignore-duration.js b/app/assets/javascripts/discourse/app/controllers/ignore-duration.js
index 929581be2ef..77e77f3e95e 100644
--- a/app/assets/javascripts/discourse/app/controllers/ignore-duration.js
+++ b/app/assets/javascripts/discourse/app/controllers/ignore-duration.js
@@ -18,7 +18,7 @@ export default Controller.extend(ModalFunctionality, {
       this.set("loading", true);
       this.model
         .updateNotificationLevel({
-          level: "ignored",
+          level: "ignore",
           expiringAt: this.ignoredUntil,
         })
         .then(() => {
diff --git a/app/assets/javascripts/discourse/app/controllers/user.js b/app/assets/javascripts/discourse/app/controllers/user.js
index 49199aafd78..9567758f050 100644
--- a/app/assets/javascripts/discourse/app/controllers/user.js
+++ b/app/assets/javascripts/discourse/app/controllers/user.js
@@ -168,14 +168,19 @@ export default Controller.extend(CanCheckEmails, {
     "currentUser.ignored_ids",
     "model.ignored",
     "model.muted",
-    function () {
-      if (this.get("model.ignored")) {
-        return "changeToIgnored";
-      } else if (this.get("model.muted")) {
-        return "changeToMuted";
-      } else {
-        return "changeToNormal";
-      }
+    {
+      get() {
+        if (this.get("model.ignored")) {
+          return "changeToIgnored";
+        } else if (this.get("model.muted")) {
+          return "changeToMuted";
+        } else {
+          return "changeToNormal";
+        }
+      },
+      set(key, value) {
+        return value;
+      },
     }
   ),
 
@@ -250,7 +255,7 @@ export default Controller.extend(CanCheckEmails, {
     },
 
     updateNotificationLevel(level) {
-      return this.model.updateNotificationLevel({ level });
+      return this.model.updateNotificationLevel(level);
     },
   },
 });
diff --git a/app/assets/javascripts/discourse/app/templates/modal/ignore-duration.hbs b/app/assets/javascripts/discourse/app/templates/modal/ignore-duration.hbs
index cabbb66960a..566b60f21a7 100644
--- a/app/assets/javascripts/discourse/app/templates/modal/ignore-duration.hbs
+++ b/app/assets/javascripts/discourse/app/templates/modal/ignore-duration.hbs
@@ -11,7 +11,7 @@
 {{/d-modal-body}}
 
 <div class="modal-footer">
-  {{d-button class="btn-primary"
+  {{d-button class="btn-primary ignore-duration-save"
              disabled=saveDisabled
              label="user.user_notifications.ignore_duration_save"
              action=(action "ignore")}}
diff --git a/app/assets/javascripts/discourse/tests/acceptance/user-test.js b/app/assets/javascripts/discourse/tests/acceptance/user-test.js
index 121ccb9e486..1485f8223a0 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/user-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/user-test.js
@@ -2,6 +2,7 @@ import EmberObject from "@ember/object";
 import User from "discourse/models/user";
 import selectKit from "discourse/tests/helpers/select-kit-helper";
 import sinon from "sinon";
+import userFixtures from "discourse/tests/fixtures/user-fixtures";
 import {
   acceptance,
   exists,
@@ -9,6 +10,7 @@ import {
   queryAll,
 } from "discourse/tests/helpers/qunit-helpers";
 import { click, currentRouteName, visit } from "@ember/test-helpers";
+import { cloneJSON } from "discourse-common/lib/object";
 import { test } from "qunit";
 
 acceptance("User Routes", function (needs) {
@@ -177,3 +179,118 @@ acceptance("User - Saving user options", function (needs) {
     );
   });
 });
+
+acceptance("User - Notification level dropdown visibility", function (needs) {
+  needs.user({ username: "eviltrout", id: 1, ignored_ids: [] });
+
+  needs.pretender((server, helper) => {
+    server.get("/u/charlie.json", () => {
+      const cloned = cloneJSON(userFixtures["/u/charlie.json"]);
+      cloned.user.can_ignore_user = false;
+      cloned.user.can_mute_user = false;
+      return helper.response(200, cloned);
+    });
+  });
+
+  test("Notification level button is not rendered for user who cannot mute or ignore another user", async function (assert) {
+    await visit("/u/charlie");
+    assert.notOk(exists(".user-notifications-dropdown"));
+  });
+});
+
+acceptance(
+  "User - Muting other user with notification level dropdown",
+  function (needs) {
+    needs.user({ username: "eviltrout", id: 1, ignored_ids: [] });
+
+    needs.pretender((server, helper) => {
+      server.get("/u/charlie.json", () => {
+        const cloned = cloneJSON(userFixtures["/u/charlie.json"]);
+        cloned.user.can_mute_user = true;
+        return helper.response(200, cloned);
+      });
+
+      server.put("/u/charlie/notification_level.json", (request) => {
+        let requestParams = new URLSearchParams(request.requestBody);
+        // Ensure the correct `notification_level` param is sent to the server
+        if (requestParams.get("notification_level") === "mute") {
+          return helper.response(200, {});
+        } else {
+          return helper.response(422, {});
+        }
+      });
+    });
+
+    test("Notification level is set to normal and can be changed to muted", async function (assert) {
+      await visit("/u/charlie");
+      assert.ok(
+        exists(".user-notifications-dropdown"),
+        "Notification level dropdown is present"
+      );
+
+      const dropdown = selectKit(".user-notifications-dropdown");
+      await dropdown.expand();
+      assert.strictEqual(dropdown.selectedRow().value(), "changeToNormal");
+
+      await dropdown.selectRowByValue("changeToMuted");
+      await dropdown.expand();
+      assert.strictEqual(dropdown.selectedRow().value(), "changeToMuted");
+    });
+  }
+);
+
+acceptance(
+  "User - Ignoring other user with notification level dropdown",
+  function (needs) {
+    needs.user({ username: "eviltrout", id: 1, ignored_ids: [] });
+
+    needs.pretender((server, helper) => {
+      server.get("/u/charlie.json", () => {
+        const cloned = cloneJSON(userFixtures["/u/charlie.json"]);
+        cloned.user.can_ignore_user = true;
+        return helper.response(200, cloned);
+      });
+
+      server.put("/u/charlie/notification_level.json", (request) => {
+        let requestParams = new URLSearchParams(request.requestBody);
+        // Ensure the correct `notification_level` param is sent to the server
+        if (requestParams.get("notification_level") === "ignore") {
+          return helper.response(200, {});
+        } else {
+          return helper.response(422, {});
+        }
+      });
+    });
+    test("Notification level can be changed to ignored", async function (assert) {
+      await visit("/u/charlie");
+      assert.ok(
+        exists(".user-notifications-dropdown"),
+        "Notification level dropdown is present"
+      );
+
+      const notificationLevelDropdown = selectKit(
+        ".user-notifications-dropdown"
+      );
+      await notificationLevelDropdown.expand();
+      assert.strictEqual(
+        notificationLevelDropdown.selectedRow().value(),
+        "changeToNormal"
+      );
+
+      await notificationLevelDropdown.selectRowByValue("changeToIgnored");
+      assert.ok(exists(".ignore-duration-modal"));
+
+      const durationDropdown = selectKit(
+        ".ignore-duration-modal .future-date-input-selector"
+      );
+      await durationDropdown.expand();
+      await durationDropdown.selectRowByIndex(0);
+      await click(".modal-footer .ignore-duration-save");
+      await notificationLevelDropdown.expand();
+      assert.strictEqual(
+        notificationLevelDropdown.selectedRow().value(),
+        "changeToIgnored"
+      );
+    });
+  }
+);
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 659a4cb221a..5c721ac698b 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1365,6 +1365,8 @@ class UsersController < ApplicationController
     elsif params[:notification_level] == "normal"
       MutedUser.where(user: acting_user, muted_user: target_user).delete_all
       IgnoredUser.where(user: acting_user, ignored_user: target_user).delete_all
+    else
+      return render_json_error(I18n.t("notification_level.invalid_value", value: params[:notification_level]))
     end
 
     render json: success_json
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 7530935ff5b..25c7e2678df 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -5154,6 +5154,7 @@ en:
     ignore_error: "Sorry, you can't ignore that user."
     mute_error: "Sorry, you can't mute that user."
     error: "Sorry, you cannot change the notification level for that user."
+    invalid_value: '"%{value}" is not a valid notification level.'
 
   discord:
     not_in_allowed_guild: "Authentication failed. You are not a member of a permitted Discord guild."
diff --git a/spec/requests/users_controller_spec.rb b/spec/requests/users_controller_spec.rb
index bd5cc682834..c978b8cc057 100644
--- a/spec/requests/users_controller_spec.rb
+++ b/spec/requests/users_controller_spec.rb
@@ -2876,6 +2876,16 @@ describe UsersController do
     end
   end
 
+  describe "#notification_level" do
+    it 'raises an error when `notification_level` param is not a valid value' do
+      sign_in(user)
+      invalid_arg = "invalid"
+      put "/u/#{user.username}/notification_level.json", params: { notification_level: invalid_arg }
+      expect(response.status).to eq(422)
+      expect(response.parsed_body["errors"].first).to eq(I18n.t("notification_level.invalid_value", value: invalid_arg))
+    end
+  end
+
   describe '#ignore' do
     it 'raises an error when not logged in' do
       put "/u/#{user1.username}/notification_level.json", params: { notification_level: "" }