diff --git a/packages/hydrooj/src/entry/cli.ts b/packages/hydrooj/src/entry/cli.ts
index 1a4d7d806..863625650 100644
--- a/packages/hydrooj/src/entry/cli.ts
+++ b/packages/hydrooj/src/entry/cli.ts
@@ -63,7 +63,7 @@ async function cli() {
         return console.error(parameters.join(', '));
     }
     for (let i = 0; i < args.length; i++) {
-        if (ObjectID.isValid(args[i])) {
+        if (args[i].length === 24 && ObjectID.isValid(args[i])) {
             args[i] = new ObjectID(args[i]);
         }
     }
diff --git a/packages/hydrooj/src/model/user.ts b/packages/hydrooj/src/model/user.ts
index 214d2ce0d..102b38754 100644
--- a/packages/hydrooj/src/model/user.ts
+++ b/packages/hydrooj/src/model/user.ts
@@ -249,14 +249,12 @@ class UserModel {
 
     @ArgMethod
     static async setSuperAdmin(uid: number) {
-        await UserModel.setPriv(uid, PRIV.PRIV_ALL);
-        return uid;
+        return await UserModel.setPriv(uid, PRIV.PRIV_ALL);
     }
 
     @ArgMethod
     static async setJudge(uid: number) {
-        await UserModel.setPriv(uid, PRIV.PRIV_USER_PROFILE | PRIV.PRIV_JUDGE);
-        return uid;
+        return await UserModel.setPriv(uid, PRIV.PRIV_USER_PROFILE | PRIV.PRIV_JUDGE);
     }
 
     @ArgMethod
diff --git a/packages/hydrooj/src/service/server.ts b/packages/hydrooj/src/service/server.ts
index 6b72d8042..4d6e63b66 100644
--- a/packages/hydrooj/src/service/server.ts
+++ b/packages/hydrooj/src/service/server.ts
@@ -16,7 +16,6 @@ import proxy from 'koa-proxies';
 import cache from 'koa-static-cache';
 import sockjs from 'sockjs';
 import type { SetOption } from 'cookies';
-import serialize, { SerializeJSOptions } from 'serialize-javascript';
 import { argv } from 'yargs';
 import { createHash } from 'crypto';
 import * as bus from './bus';
@@ -27,7 +26,7 @@ import {
     UserNotFoundError, BlacklistedError, PermissionError,
     UserFacingError, ValidationError, PrivilegeError,
     CsrfTokenError, InvalidOperationError, MethodNotAllowedError,
-    NotFoundError, HydroError,
+    NotFoundError, HydroError, SystemError,
 } from '../error';
 import * as misc from '../lib/misc';
 import { isContent, isName, isTitle } from '../lib/validator';
@@ -483,7 +482,7 @@ export class Handler extends HandlerCommon {
     }
 
     async init({ domainId }) {
-        if (!argv.benchmark) await this.limitRate('global', 10, 50);
+        if (!argv.benchmark) await this.limitRate('global', 10, 88);
         const [absoluteDomain, inferDomain] = await Promise.all([
             domain.get(domainId),
             domain.getByHost(this.request.host),
@@ -551,11 +550,9 @@ export class Handler extends HandlerCommon {
             this.request.json || this.response.redirect
             || this.request.query.noTemplate || !this.response.template) {
             try {
-                this.response.body = JSON.stringify(this.response.body);
+                this.response.body = JSON.stringify(this.response.body, serializer, 2);
             } catch (e) {
-                const opt: SerializeJSOptions = { ignoreFunction: true };
-                if (this.request.query.noTemplate) opt.space = 2;
-                this.response.body = serialize(this.response.body, opt);
+                this.response.body = new SystemError('Serialize failure', e.message);
             }
             this.response.type = 'application/json';
         } else if (this.response.body || this.response.template) {