diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index c64731170..f5875d58e 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.28.4",
+    "version": "2.28.5",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",
diff --git a/packages/hydrooj/src/handler/contest.ts b/packages/hydrooj/src/handler/contest.ts
index 7b511b8a3..dd89a62ce 100644
--- a/packages/hydrooj/src/handler/contest.ts
+++ b/packages/hydrooj/src/handler/contest.ts
@@ -6,9 +6,7 @@ import {
     ContestNotLiveError, ValidationError, ProblemNotFoundError,
     ContestNotAttendedError, PermissionError, BadRequestError,
 } from '../error';
-import {
-    ProblemId, ProblemDoc, Tdoc, User,
-} from '../interface';
+import { ProblemDoc, Tdoc, User } from '../interface';
 import paginate from '../lib/paginate';
 import { PERM, PRIV } from '../model/builtin';
 import * as contest from '../model/contest';
@@ -79,6 +77,7 @@ export class ContestDetailHandler extends Handler {
         for (const key in pdict) {
             // @ts-ignore
             if (pdict[key].domainId !== domainId) pdict[key].docId = `${pdict[key].domainId}:${pdict[key].docId}`;
+            pdict[key].pid = (tdoc.pids.indexOf(pdict[key].docId) + 10).toString(36).toUpperCase();
         }
         this.response.body = {
             path, tdoc, tsdoc, attended, udict, pdict, psdict, rdict, page,
@@ -102,7 +101,7 @@ export class ContestDetailHandler extends Handler {
     }
 }
 
-class ContestBoardcastHandler extends Handler {
+export class ContestBoardcastHandler extends Handler {
     @param('tid', Types.ObjectID)
     async get(domainId: string, tid: ObjectID) {
         const tdoc = await contest.get(domainId, tid);
@@ -131,7 +130,7 @@ class ContestBoardcastHandler extends Handler {
     }
 }
 
-class ContestScoreboardHandler extends Handler {
+export class ContestScoreboardHandler extends Handler {
     @param('tid', Types.ObjectID)
     @param('page', Types.PositiveInt, true)
     async get(domainId: string, tid: ObjectID, page = 1) {
@@ -149,7 +148,7 @@ class ContestScoreboardHandler extends Handler {
     }
 }
 
-class ContestScoreboardDownloadHandler extends Handler {
+export class ContestScoreboardDownloadHandler extends Handler {
     @param('tid', Types.ObjectID)
     @param('ext', Types.Range(['csv', 'html']))
     async get(domainId: string, tid: ObjectID, ext: string) {
@@ -253,15 +252,17 @@ export class ContestProblemHandler extends Handler {
 
     @param('tid', Types.ObjectID)
     @param('pid', Types.Name)
-    async _prepare(domainId: string, tid: ObjectID, pid: ProblemId) {
+    async _prepare(domainId: string, tid: ObjectID, _pid: string) {
         this.tdoc = await contest.get(domainId, tid);
-        if (!this.tdoc.pids.includes(pid)) throw new ProblemNotFoundError(domainId, pid);
+        const pid = this.tdoc.pids[parseInt(_pid, 36) - 10];
+        if (!pid) throw new ProblemNotFoundError(domainId, tid, _pid);
         [this.pdoc, this.tsdoc, this.udoc] = await Promise.all([
             problem.get(domainId, pid),
             contest.getStatus(domainId, tid, this.user._id),
             user.getById(domainId, this.tdoc.owner),
         ]);
         if (!this.pdoc) throw new ProblemNotFoundError(domainId, pid);
+        this.pdoc.pid = _pid;
         // @ts-ignore
         if (this.pdoc.domainId !== domainId) this.pdoc.docId = `${this.pdoc.domainId}:${this.pdoc.docId}`;
         this.attended = this.tsdoc && this.tsdoc.attend === 1;
@@ -316,7 +317,8 @@ export class ContestDetailProblemSubmitHandler extends ContestProblemHandler {
 
     @param('tid', Types.ObjectID)
     @param('pid', Types.Name)
-    async get(domainId: string, tid: ObjectID, pid: ProblemId) {
+    async get(domainId: string, tid: ObjectID, _pid: string) {
+        const pid = this.tdoc.pids[parseInt(_pid, 36) - 10];
         this.response.body.rdocs = [];
         if (contest.canShowRecord.call(this, this.tdoc)) {
             this.response.body.rdocs = await record.getUserInProblemMulti(
@@ -339,7 +341,8 @@ export class ContestDetailProblemSubmitHandler extends ContestProblemHandler {
     @param('lang', Types.Name)
     @param('code', Types.Content)
     @param('pid', Types.Name)
-    async post(domainId: string, tid: ObjectID, lang: string, code: string, pid: ProblemId) {
+    async post(domainId: string, tid: ObjectID, lang: string, code: string, _pid: string) {
+        const pid = this.tdoc.pids[parseInt(_pid, 36) - 10];
         if (this.response.body.pdoc.config?.langs && !this.response.body.pdoc.config.langs.includes(lang)) {
             throw new BadRequestError('Language not allowed.');
         }
diff --git a/packages/hydrooj/src/handler/homework.ts b/packages/hydrooj/src/handler/homework.ts
index 5b81d8b7d..743a679ce 100644
--- a/packages/hydrooj/src/handler/homework.ts
+++ b/packages/hydrooj/src/handler/homework.ts
@@ -8,7 +8,7 @@ import {
     HomeworkNotAttendedError, BadRequestError,
 } from '../error';
 import {
-    PenaltyRules, Tdoc, ProblemDoc, User, ProblemId,
+    PenaltyRules, Tdoc, ProblemDoc, User,
 } from '../interface';
 import {
     Route, Handler, Types, param, query,
@@ -25,7 +25,6 @@ import record from '../model/record';
 import storage from '../model/storage';
 import * as document from '../model/document';
 import paginate from '../lib/paginate';
-import { isExternalPid } from '../lib/validator';
 
 const validatePenaltyRules = (input: string) => yaml.load(input);
 const convertPenaltyRules = validatePenaltyRules;
@@ -94,6 +93,7 @@ class HomeworkDetailHandler extends Handler {
         for (const key in pdict) {
             // @ts-ignore
             if (pdict[key].domainId !== domainId) pdict[key].docId = `${pdict[key].domainId}:${pdict[key].docId}`;
+            pdict[key].pid = (tdoc.pids.indexOf(pdict[key].docId) + 10).toString(36).toUpperCase();
         }
         this.response.template = 'homework_detail.html';
         this.response.body = {
@@ -127,17 +127,19 @@ class HomeworkDetailProblemHandler extends Handler {
     attended: boolean;
 
     @param('tid', Types.ObjectID)
-    @param('pid', Types.String, isExternalPid)
-    async _prepare(domainId: string, tid: ObjectID, pid: ProblemId) {
-        if (!this.tdoc.pids.includes(pid)) throw new ProblemNotFoundError(domainId, pid, tid);
+    @param('pid', Types.String)
+    async _prepare(domainId: string, tid: ObjectID, _pid: string) {
+        this.tdoc = await contest.get(domainId, tid, document.TYPE_HOMEWORK);
+        const pid = this.tdoc.pids[parseInt(_pid, 36) - 10];
+        if (!pid) throw new ProblemNotFoundError(domainId, tid, _pid);
         const pdomainId = typeof pid === 'string' ? pid.split(':')[0] : domainId;
         const ppid = typeof pid === 'number' ? pid : +pid.split(':')[1];
-        [this.tdoc, this.pdoc, this.tsdoc] = await Promise.all([
-            contest.get(domainId, tid, document.TYPE_HOMEWORK),
+        [this.udoc, this.pdoc, this.tsdoc] = await Promise.all([
+            user.getById(domainId, this.tdoc.owner),
             problem.get(pdomainId, ppid),
             contest.getStatus(domainId, tid, this.user._id, document.TYPE_HOMEWORK),
         ]);
-        this.udoc = await user.getById(domainId, this.tdoc.owner);
+        this.pdoc.pid = _pid;
         this.attended = this.tsdoc && this.tsdoc.attend === 1;
         this.response.body = {
             tdoc: this.tdoc,
@@ -150,8 +152,7 @@ class HomeworkDetailProblemHandler extends Handler {
 
     @param('tid', Types.ObjectID)
     @param('pid', Types.Name)
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    async get(domainId: string, tid: ObjectID, pid: ProblemId) {
+    async get(domainId: string, tid: ObjectID, pid: string) {
         if (!contest.isDone(this.tdoc)) {
             if (!this.attended) throw new HomeworkNotAttendedError(tid);
             if (contest.isNotStarted(this.tdoc)) throw new HomeworkNotLiveError(tid);
@@ -195,8 +196,9 @@ class HomeworkDetailProblemSubmitHandler extends HomeworkDetailProblemHandler {
     }
 
     @param('tid', Types.ObjectID)
-    @param('pid', Types.String, isExternalPid)
-    async get(domainId: string, tid: ObjectID, pid: ProblemId) {
+    @param('pid', Types.String)
+    async get(domainId: string, tid: ObjectID, _pid: string) {
+        const pid = this.tdoc.pids[parseInt(_pid, 36) - 10];
         this.response.body.rdocs = contest.canShowRecord.call(this, this.tdoc)
             ? await record.getUserInProblemMulti(domainId, this.user._id, pid, { type: document.TYPE_HOMEWORK, tid })
                 .sort('_id', -1).limit(10).toArray()
@@ -212,10 +214,11 @@ class HomeworkDetailProblemSubmitHandler extends HomeworkDetailProblemHandler {
     }
 
     @param('tid', Types.ObjectID)
-    @param('pid', Types.String, isExternalPid)
+    @param('pid', Types.String)
     @param('code', Types.Content)
     @param('lang', Types.Name)
-    async post(domainId: string, tid: ObjectID, pid: ProblemId, code: string, lang: string) {
+    async post(domainId: string, tid: ObjectID, _pid: string, code: string, lang: string) {
+        const pid = this.tdoc.pids[parseInt(_pid, 36) - 10];
         if (this.response.body.pdoc.config?.langs && !this.response.body.pdoc.config.langs.includes(lang)) {
             throw new BadRequestError('Language not allowed.');
         }
diff --git a/packages/hydrooj/src/loader.ts b/packages/hydrooj/src/loader.ts
index 477dd8d87..d0f7cd7ec 100644
--- a/packages/hydrooj/src/loader.ts
+++ b/packages/hydrooj/src/loader.ts
@@ -120,6 +120,7 @@ async function reload(count = 1) {
 
 const shell = new Logger('shell');
 async function executeCommand(input: string) {
+    input = input.trim();
     // Clear the stack
     setImmediate(async () => {
         if (input === 'restart') return reload();
@@ -128,7 +129,7 @@ async function executeCommand(input: string) {
         }
         try {
             // eslint-disable-next-line no-eval
-            shell.info(await eval(input.trim()));
+            shell.info(await eval(input));
         } catch (e) {
             shell.warn(e);
         }
diff --git a/packages/hydrooj/src/model/problem.ts b/packages/hydrooj/src/model/problem.ts
index 84d93857a..a9ea3ef64 100644
--- a/packages/hydrooj/src/model/problem.ts
+++ b/packages/hydrooj/src/model/problem.ts
@@ -247,8 +247,8 @@ export class ProblemModel {
         const l = {};
         const ddocs = await Promise.all(Object.keys(parsed).map((i) => domain.get(i)));
         const f = ddocs.filter((i) => !(
-            i.share === '*'
-            || (`,${(i.share || '').replace(/，/g, ',').split(',').map((q) => q.trim()).join(',')},`).includes(`,${domainId},`)
+            i?.share === '*'
+            || (`,${(i?.share || '').replace(/，/g, ',').split(',').map((q) => q.trim()).join(',')},`).includes(`,${domainId},`)
         ));
         if (f.length) {
             if (doThrow) throw new ProblemNotFoundError(f[0]._id, parsed[f[0]._id][0].pid);
diff --git a/packages/ui-default/package.json b/packages/ui-default/package.json
index f3971cd64..d6953c19b 100644
--- a/packages/ui-default/package.json
+++ b/packages/ui-default/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.11.0",
+  "version": "4.11.1",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "hydro.js",
diff --git a/packages/ui-default/templates/components/problem.html b/packages/ui-default/templates/components/problem.html
index cd2543a0d..49b1c09fc 100644
--- a/packages/ui-default/templates/components/problem.html
+++ b/packages/ui-default/templates/components/problem.html
@@ -2,15 +2,15 @@
 {%- if not invalid %}
   <a
   {%- if tdoc and tdoc.docType == model.document.TYPE_CONTEST %}
-    href="{{ url('contest_detail_problem', tid=tdoc.docId, pid=pdoc.docId) }}"
+    href="{{ url('contest_detail_problem', tid=tdoc.docId, pid=pdoc.pid) }}"
   {%- elif tdoc and tdoc.docType == model.document.TYPE_HOMEWORK %}
-    href="{{ url('homework_detail_problem', tid=tdoc.docId, pid=pdoc.docId) }}"
+    href="{{ url('homework_detail_problem', tid=tdoc.docId, pid=pdoc.pid) }}"
   {%- else %}
     href="{{ url('problem_detail', pid=pdoc.pid|default(pdoc.docId)) }}"
   {%- endif %}
   >
 {%- endif %}
-{{ pdoc.pid if pdoc.pid else 'P'+pdoc.docId }} {{ pdoc.title }}
+{{ pdoc.pid if pdoc.pid else 'P'+pdoc.docId }}. {{ pdoc.title }}
 {%- if not invalid %}
   </a>
 {%- endif %}
diff --git a/packages/ui-default/templates/contest_detail.html b/packages/ui-default/templates/contest_detail.html
index aa28d4f3b..3146c8ff1 100644
--- a/packages/ui-default/templates/contest_detail.html
+++ b/packages/ui-default/templates/contest_detail.html
@@ -57,7 +57,6 @@
               {% endif %}
             {% endif %}
               <td class="col--problem col--problem-name">
-                #{{ loop.index }}:
                 {{ problem.render_problem_title(pdict[pid], tdoc=tdoc, show_invisible_flag=false, show_tags=false) }}
               </td>
             </tr>