diff --git a/CHANGELOG.md b/CHANGELOG.md
index 63448a6ae5b..fc6569bb2dc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ### General
 - Feat: ジョブキュー管理画面からキューの一時停止/再開ができるように
 - Feat: アンテナのタイムラインから個別のノートを削除できるように
+- Fix: コンパネからrootユーザーのパスワードをリセットしようとした際にエラーが通知されない問題を修正
 - Feat: ノート検索で投稿日時の期間を条件に加えられるように(#16035)
 
 ### Client
diff --git a/packages/backend/src/server/api/endpoints/admin/reset-password.ts b/packages/backend/src/server/api/endpoints/admin/reset-password.ts
index fc246631c29..f19ffa173bc 100644
--- a/packages/backend/src/server/api/endpoints/admin/reset-password.ts
+++ b/packages/backend/src/server/api/endpoints/admin/reset-password.ts
@@ -6,6 +6,7 @@
 import { Inject, Injectable } from '@nestjs/common';
 import bcrypt from 'bcryptjs';
 import { Endpoint } from '@/server/api/endpoint-base.js';
+import { ApiError } from '@/server/api/error.js';
 import type { UsersRepository, UserProfilesRepository, MiMeta } from '@/models/_.js';
 import { DI } from '@/di-symbols.js';
 import { secureRndstr } from '@/misc/secure-rndstr.js';
@@ -18,6 +19,19 @@ export const meta = {
 	requireModerator: true,
 	kind: 'write:admin:reset-password',
 
+	errors: {
+		noSuchUser: {
+			message: 'No such user.',
+			code: 'NO_SUCH_USER',
+			id: 'ccafc7fe-5074-4edd-9dc0-8ef9ef6a701d',
+		},
+		cannotResetPasswordOfRootUser: {
+			message: 'Cannot reset password of the root user.',
+			code: 'CANNOT_RESET_PASSWORD_OF_ROOT_USER',
+			id: 'f28fc207-42ca-44c7-a577-44b4f0ec5999',
+		},
+	},
+
 	res: {
 		type: 'object',
 		optional: false, nullable: false,
@@ -58,11 +72,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			const user = await this.usersRepository.findOneBy({ id: ps.userId });
 
 			if (user == null) {
-				throw new Error('user not found');
+				throw new ApiError(meta.errors.noSuchUser);
 			}
 
 			if (this.serverSettings.rootUserId === user.id) {
-				throw new Error('cannot reset password of root');
+				throw new ApiError(meta.errors.cannotResetPasswordOfRootUser);
 			}
 
 			const passwd = secureRndstr(8);
diff --git a/packages/frontend/src/pages/admin-user.vue b/packages/frontend/src/pages/admin-user.vue
index b084eb5ab2d..e8e5475729a 100644
--- a/packages/frontend/src/pages/admin-user.vue
+++ b/packages/frontend/src/pages/admin-user.vue
@@ -334,7 +334,7 @@ async function resetPassword() {
 	if (confirm.canceled) {
 		return;
 	} else {
-		const { password } = await misskeyApi('admin/reset-password', {
+		const { password } = await os.apiWithDialog('admin/reset-password', {
 			userId: user.value.id,
 		});
 		os.alert({