diff --git a/models/contest.js b/models/contest.js
index 4d83542..309a7c7 100644
--- a/models/contest.js
+++ b/models/contest.js
@@ -112,7 +112,7 @@ class Contest extends Model {
 
   async newSubmission(judge_state) {
     let problems = await this.getProblems();
-    if (!problems.includes(judge_state.problem_id)) throw 'No such problem in contest.';
+    if (!problems.includes(judge_state.problem_id)) throw new ErrorMessage('当前比赛中无此题目。');
 
     let player = await ContestPlayer.findInContest({
       contest_id: this.id,
diff --git a/models/problem.js b/models/problem.js
index 5cbaea7..5b099f0 100644
--- a/models/problem.js
+++ b/models/problem.js
@@ -246,7 +246,7 @@ class Problem extends Model {
 
     let buf = await fs.readFileAsync(path);
 
-    if (buf.length > syzoj.config.limit.data_size) throw 'Testdata too large.'
+    if (buf.length > syzoj.config.limit.data_size) throw new ErrorMessage('测试数据太大。');
 
     let key = syzoj.utils.md5(buf);
     await fs.moveAsync(path, TestData.resolvePath(key), { overwrite: true });
diff --git a/modules/api.js b/modules/api.js
index bb7013e..140644c 100644
--- a/modules/api.js
+++ b/modules/api.js
@@ -83,36 +83,6 @@ app.post('/api/markdown', async (req, res) => {
   }
 });
 
-// Set problem public
-async function setPublic(req, res, is_public) {
-  try {
-    let id = parseInt(req.params.id);
-    let problem = await Problem.fromID(id);
-    if (!problem) throw 'No such problem';
-
-    let allowedEdit = await problem.isAllowedEditBy(res.locals.user);
-    if (!allowedEdit) throw 'Permission denied';
-
-    problem.is_public = is_public;
-    await problem.save();
-
-    res.send({});
-  } catch (e) {
-    syzoj.log(e);
-    res.render('error', {
-      err: e
-    });
-  }
-}
-
-app.post('/api/problem/:id/public', async (req, res) => {
-  await setPublic(req, res, true);
-});
-
-app.delete('/api/problem/:id/public', async (req, res) => {
-  await setPublic(req, res, false);
-});
-
 // APIs for judge client
 app.get('/api/waiting_judge', async (req, res) => {
   try {
diff --git a/modules/contest.js b/modules/contest.js
index ef3d5cc..bbf89e0 100644
--- a/modules/contest.js
+++ b/modules/contest.js
@@ -47,7 +47,7 @@ app.get('/contests', async (req, res) => {
 
 app.get('/contest/:id/edit', async (req, res) => {
   try {
-    if (!res.locals.user || !res.locals.user.is_admin) throw 'Permission denied.';
+    if (!res.locals.user || !res.locals.user.is_admin) throw new ErrorMessage('您没有权限进行此操作。');
 
     let contest_id = parseInt(req.params.id);
     let contest = await Contest.fromID(contest_id);
@@ -73,7 +73,7 @@ app.get('/contest/:id/edit', async (req, res) => {
 
 app.post('/contest/:id/edit', async (req, res) => {
   try {
-    if (!res.locals.user || !res.locals.user.is_admin) throw 'Permission denied.';
+    if (!res.locals.user || !res.locals.user.is_admin) throw new ErrorMessage('您没有权限进行此操作。');
 
     let contest_id = parseInt(req.params.id);
     let contest = await Contest.fromID(contest_id);
@@ -110,7 +110,7 @@ app.get('/contest/:id', async (req, res) => {
     let contest_id = parseInt(req.params.id);
 
     let contest = await Contest.fromID(contest_id);
-    if (!contest) throw 'No such contest.';
+    if (!contest) throw new ErrorMessage('无此比赛。');
 
     contest.allowedEdit = await contest.isAllowedEditBy(res.locals.user);
     contest.running = await contest.isRunning();
@@ -163,9 +163,9 @@ app.get('/contest/:id/ranklist', async (req, res) => {
   try {
     let contest_id = parseInt(req.params.id);
     let contest = await Contest.fromID(contest_id);
-    if (!contest) throw 'No such contest.';
+    if (!contest) throw new ErrorMessage('无此比赛。');
 
-    if (!await contest.isAllowedSeeResultBy(res.locals.user)) throw 'Permission denied';
+    if (!await contest.isAllowedSeeResultBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
     await contest.loadRelationships();
 
@@ -207,7 +207,7 @@ app.get('/contest/:id/submissions', async (req, res) => {
     let contest_id = parseInt(req.params.id);
     let contest = await Contest.fromID(contest_id);
 
-    if (!contest) throw 'No such contest.';
+    if (!contest) throw new ErrorMessage('无此比赛。');
 
     contest.ended = await contest.isEnded();
 
@@ -268,12 +268,12 @@ app.get('/contest/:id/:pid', async (req, res) => {
     let contest = await Contest.fromID(contest_id);
 
     contest.ended = await contest.isEnded();
-    if (!(await contest.isRunning() || contest.ended)) throw 'The contest has not started.'
+    if (!(await contest.isRunning() || contest.ended)) throw new ErrorMessage('比赛尚未开始或已结束。');
 
     let problems_id = await contest.getProblems();
 
     let pid = parseInt(req.params.pid);
-    if (!pid || pid < 1 || pid > problems_id.length) throw 'No such problem.';
+    if (!pid || pid < 1 || pid > problems_id.length) throw new ErrorMessage('无此题目。');
 
     let problem_id = problems_id[pid - 1];
     let problem = await Problem.fromID(problem_id);
diff --git a/modules/discussion.js b/modules/discussion.js
index 5b15f13..5b0f116 100644
--- a/modules/discussion.js
+++ b/modules/discussion.js
@@ -46,7 +46,7 @@ app.get('/article/:id', async (req, res) => {
   try {
     let id = parseInt(req.params.id);
     let article = await Article.fromID(id);
-    if (!article) throw 'No such article';
+    if (!article) throw new ErrorMessage('无此帖子。');
 
     await article.loadRelationships();
     article.allowedEdit = await article.isAllowedEditBy(res.locals.user);
@@ -80,7 +80,7 @@ app.get('/article/:id', async (req, res) => {
 
 app.get('/article/:id/edit', async (req, res) => {
   try {
-    if (!res.locals.user) throw 'Please login.';
+    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
 
     let id = parseInt(req.params.id);
     let article = await Article.fromID(id);
@@ -106,7 +106,7 @@ app.get('/article/:id/edit', async (req, res) => {
 
 app.post('/article/:id/edit', async (req, res) => {
   try {
-    if (!res.locals.user) throw 'Please login.';
+    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
 
     let id = parseInt(req.params.id);
     let article = await Article.fromID(id);
@@ -117,7 +117,7 @@ app.post('/article/:id/edit', async (req, res) => {
       article.user_id = res.locals.user.id;
       article.public_time = article.sort_time = time;
     } else {
-      if (!await article.isAllowedEditBy(res.locals.user)) throw 'Permission denied.';
+      if (!await article.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     article.title = req.body.title;
@@ -137,15 +137,15 @@ app.post('/article/:id/edit', async (req, res) => {
 
 app.get('/article/:id/delete', async (req, res) => {
   try {
-    if (!res.locals.user) throw 'Please login.';
+    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
 
     let id = parseInt(req.params.id);
     let article = await Article.fromID(id);
 
     if (!article) {
-      throw 'No such article.';
+      throw new ErrorMessage('无此帖子。');
     } else {
-      if (!await article.isAllowedEditBy(res.locals.user)) throw 'Permission denied.';
+      if (!await article.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     await article.destroy();
@@ -161,15 +161,15 @@ app.get('/article/:id/delete', async (req, res) => {
 
 app.post('/article/:id/comment', async (req, res) => {
   try {
-    if (!res.locals.user) throw 'Please login.';
+    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
 
     let id = parseInt(req.params.id);
     let article = await Article.fromID(id);
 
     if (!article) {
-      throw 'No such article.';
+      throw new ErrorMessage('无此帖子。');
     } else {
-      if (!await article.isAllowedCommentBy(res.locals.user)) throw 'Permission denied.';
+      if (!await article.isAllowedCommentBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     let comment = await ArticleComment.create({
@@ -192,15 +192,15 @@ app.post('/article/:id/comment', async (req, res) => {
 
 app.get('/article/:article_id/comment/:id/delete', async (req, res) => {
   try {
-    if (!res.locals.user) throw 'Please login.';
+    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
 
     let id = parseInt(req.params.id);
     let comment = await ArticleComment.fromID(id);
 
     if (!comment) {
-      throw 'No such comment.';
+      throw new ErrorMessage('无此评论。');
     } else {
-      if (!await comment.isAllowedEditBy(res.locals.user)) throw 'Permission denied.';
+      if (!await comment.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     await comment.destroy();
diff --git a/modules/index.js b/modules/index.js
index f74aa76..7d1c76a 100644
--- a/modules/index.js
+++ b/modules/index.js
@@ -33,7 +33,7 @@ app.get('/', async (req, res) => {
       if (notice.type === 'link') return notice;
       else if (notice.type === 'article') {
         let article = await Article.fromID(notice.id);
-        if (!article) throw `No such article ${notice.id}`;
+        if (!article) throw new ErrorMessage(`无此帖子：${notice.id}`);
         return {
           title: article.title,
           url: syzoj.utils.makeUrl(['article', article.id]),
diff --git a/modules/problem.js b/modules/problem.js
index 5ef2978..4e80ebb 100644
--- a/modules/problem.js
+++ b/modules/problem.js
@@ -130,10 +130,10 @@ app.get('/problem/:id', async (req, res) => {
   try {
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
-    if (!problem) throw 'No such problem.';
+    if (!problem) throw new ErrorMessage('无此题目。');
 
     if (!await problem.isAllowedUseBy(res.locals.user)) {
-      throw 'Permission denied.';
+      throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
@@ -141,7 +141,7 @@ app.get('/problem/:id', async (req, res) => {
     if (problem.is_public || problem.allowedEdit) {
       await syzoj.utils.markdown(problem, [ 'description', 'input_format', 'output_format', 'example', 'limit_and_hint' ]);
     } else {
-      throw 'Permission denied';
+      throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     let state = await problem.getJudgeState(res.locals.user, false);
@@ -164,7 +164,7 @@ app.get('/problem/:id/export', async (req, res) => {
   try {
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
-    if (!problem || !problem.is_public) throw 'No such problem.';
+    if (!problem || !problem.is_public) throw new ErrorMessage('无此题目。');
 
     let obj = {
       title: problem.title,
@@ -198,14 +198,14 @@ app.get('/problem/:id/edit', async (req, res) => {
     let problem = await Problem.fromID(id);
 
     if (!problem) {
-      if (!res.locals.user) throw 'Permission denied.';
+      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
       problem = await Problem.create();
       problem.id = id;
       problem.allowedEdit = true;
       problem.tags = [];
       problem.new = true;
     } else {
-      if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied.';
+      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
       problem.allowedEdit = await problem.isAllowedEditBy(res.locals.user);
       problem.tags = await problem.getTags();
     }
@@ -226,23 +226,25 @@ app.post('/problem/:id/edit', async (req, res) => {
     let id = parseInt(req.params.id) || 0;
     let problem = await Problem.fromID(id);
     if (!problem) {
+      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
+
       problem = await Problem.create();
 
       let customID = parseInt(req.body.id);
       if (customID) {
-        if (await Problem.fromID(customID)) throw 'The ID has been used.';
+        if (await Problem.fromID(customID)) throw new ErrorMessage('ID 已被使用。');
         problem.id = customID;
       } else if (id) problem.id = id;
 
       problem.user_id = res.locals.user.id;
     } else {
-      if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied.';
-      if (!await problem.isAllowedEditBy(res.locals.user)) throw 'Permission denied.';
+      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
+      if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
       if (res.locals.user.is_admin) {
         let customID = parseInt(req.body.id);
         if (customID && customID !== id) {
-          if (await Problem.fromID(customID)) throw 'The ID has been used.';
+          if (await Problem.fromID(customID)) throw new ErrorMessage('ID 已被使用。');
           await problem.changeID(customID);
         }
       }
@@ -280,14 +282,17 @@ app.get('/problem/:id/import', async (req, res) => {
   try {
     let id = parseInt(req.params.id) || 0;
     let problem = await Problem.fromID(id);
+
     if (!problem) {
+      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
+
       problem = await Problem.create();
       problem.id = id;
       problem.new = true;
       problem.user_id = res.locals.user.id;
     } else {
-      if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied.';
-      if (!await problem.isAllowedEditBy(res.locals.user)) throw 'Permission denied.';
+      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
+      if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     res.render('problem_import', {
@@ -306,18 +311,20 @@ app.post('/problem/:id/import', async (req, res) => {
     let id = parseInt(req.params.id) || 0;
     let problem = await Problem.fromID(id);
     if (!problem) {
+      if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
+
       problem = await Problem.create();
 
       let customID = parseInt(req.body.id);
       if (customID) {
-        if (await Problem.fromID(customID)) throw 'The ID has been used.';
+        if (await Problem.fromID(customID)) throw new ErrorMessage('ID 已被使用。');
         problem.id = customID;
       } else if (id) problem.id = id;
 
       problem.user_id = res.locals.user.id;
     } else {
-      if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied.';
-      if (!await problem.isAllowedEditBy(res.locals.user)) throw 'Permission denied.';
+      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
+      if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     let request = require('request-promise');
@@ -329,7 +336,7 @@ app.post('/problem/:id/import', async (req, res) => {
       json: true
     });
 
-    if (!json.success) throw `Failed to load problem: ${json.error}`;
+    if (!json.success) throw new ErrorMessage('题目加载失败。', null, json.error);
 
     problem.title = json.obj.title;
     problem.description = json.obj.description;
@@ -344,7 +351,7 @@ app.post('/problem/:id/import', async (req, res) => {
     problem.file_io_output_name = json.obj.file_io_output_name;
 
     let validateMsg = await problem.validate();
-    if (validateMsg) throw 'Invalid problem: ' + validateMsg;
+    if (validateMsg) throw new ErrorMessage('无效的题目数据配置。', null, validateMsg);
 
     await problem.save();
 
@@ -378,8 +385,8 @@ app.get('/problem/:id/data', async (req, res) => {
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
 
-    if (!problem) throw 'No such problem';
-    if (!await problem.isAllowedEditBy(res.locals.user)) throw 'Permission denied';
+    if (!problem) throw new ErrorMessage('无此题目。');
+    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
     await problem.loadRelationships();
 
@@ -399,8 +406,8 @@ app.post('/problem/:id/data', app.multer.single('testdata'), async (req, res) =>
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
 
-    if (!problem) throw 'No such problem';
-    if (!await problem.isAllowedEditBy(res.locals.user)) throw 'Permission denied';
+    if (!problem) throw new ErrorMessage('无此题目。');
+    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
     await problem.loadRelationships();
 
@@ -411,7 +418,7 @@ app.post('/problem/:id/data', app.multer.single('testdata'), async (req, res) =>
     problem.file_io_output_name = req.body.file_io_output_name;
 
     let validateMsg = await problem.validate();
-    if (validateMsg) throw 'Invalid problem: ' + validateMsg;
+    if (validateMsg) throw new ErrorMessage('无效的题目数据配置。', null, validateMsg);
 
     if (req.file) {
       await problem.updateTestdata(req.file.path);
@@ -428,14 +435,44 @@ app.post('/problem/:id/data', app.multer.single('testdata'), async (req, res) =>
   }
 });
 
+// Set problem public
+async function setPublic(req, res, is_public) {
+  try {
+    let id = parseInt(req.params.id);
+    let problem = await Problem.fromID(id);
+    if (!problem) throw new ErrorMessage('无此题目。');
+
+    let allowedEdit = await problem.isAllowedEditBy(res.locals.user);
+    if (!allowedEdit) throw new ErrorMessage('您没有权限进行此操作。');
+
+    problem.is_public = is_public;
+    await problem.save();
+
+    res.redirect(syzoj.utils.makeUrl(['problem', id]));
+  } catch (e) {
+    syzoj.log(e);
+    res.render('error', {
+      err: e
+    });
+  }
+}
+
+app.get('/problem/:id/public', async (req, res) => {
+  await setPublic(req, res, true);
+});
+
+app.get('/problem/:id/dis_public', async (req, res) => {
+  await setPublic(req, res, false);
+});
+
 app.post('/problem/:id/submit', async (req, res) => {
   try {
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
 
-    if (!problem) throw 'No such problem.';
-    if (!syzoj.config.languages[req.body.language]) throw 'No such language.'
-    if (!res.locals.user) throw 'Please login.';
+    if (!problem) throw new ErrorMessage('无此题目。');
+    if (!syzoj.config.languages[req.body.language]) throw new ErrorMessage('不支持该语言。');
+    if (!res.locals.user) throw new ErrorMessage('请登录后继续。', { '登录': syzoj.utils.makeUrl(['login'], { 'url': req.originalUrl }) });
 
     let judge_state = await JudgeState.create({
       code: req.body.code,
@@ -447,16 +484,16 @@ app.post('/problem/:id/submit', async (req, res) => {
     let contest_id = parseInt(req.query.contest_id);
     if (contest_id) {
       let contest = await Contest.fromID(contest_id);
-      if (!contest) throw 'No such contest.';
+      if (!contest) throw new ErrorMessage('无此比赛。');
       let problems_id = await contest.getProblems();
-      if (!problems_id.includes(id)) throw 'No such problem.';
+      if (!problems_id.includes(id)) throw new ErrorMessage('无此题目。');
 
       judge_state.type = 1;
       judge_state.type_info = contest_id;
 
       await judge_state.save();
     } else {
-      if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied.';
+      if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
       judge_state.type = problem.is_public ? 0 : 2;
       await judge_state.save();
     }
@@ -486,12 +523,12 @@ app.get('/problem/:id/download', async (req, res) => {
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
 
-    if (!problem) throw 'No such problem';
-    if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied';
+    if (!problem) throw new ErrorMessage('无此题目。');
+    if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
     await problem.loadRelationships();
 
-    if (!problem.testdata) throw 'No testdata';
+    if (!problem.testdata) throw new ErrorMessage('无测试数据。');
 
     res.download(problem.testdata.getPath(), `testdata_${id}.zip`);
   } catch (e) {
@@ -508,11 +545,11 @@ app.get('/problem/:id/statistics/:type', async (req, res) => {
     let id = parseInt(req.params.id);
     let problem = await Problem.fromID(id);
 
-    if (!problem) throw 'No such problem';
-    if (!await problem.isAllowedUseBy(res.locals.user)) throw 'Permission denied';
+    if (!problem) throw new ErrorMessage('无此题目。');
+    if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
     let count = await problem.countStatistics(req.params.type);
-    if (count === null) throw 'No such type';
+    if (count === null) throw new ErrorMessage('无此统计类型。');
 
     let paginate = syzoj.utils.paginate(count, req.query.page, syzoj.config.page.problem_statistics);
     let statistics = await problem.getStatistics(req.params.type, paginate);
diff --git a/modules/problem_tag.js b/modules/problem_tag.js
index 75340dd..1d130e7 100644
--- a/modules/problem_tag.js
+++ b/modules/problem_tag.js
@@ -23,7 +23,7 @@ let ProblemTag = syzoj.model('problem_tag');
 
 app.get('/problems/tag/:id/edit', async (req, res) => {
   try {
-    if (!res.locals.user && !res.locals.user.is_admin) throw 'Permission denied.';
+    if (!res.locals.user && !res.locals.user.is_admin) throw new ErrorMessage('您没有权限进行此操作。');
 
     let id = parseInt(req.params.id) || 0;
     let tag = await ProblemTag.fromID(id);
@@ -46,7 +46,7 @@ app.get('/problems/tag/:id/edit', async (req, res) => {
 
 app.post('/problems/tag/:id/edit', async (req, res) => {
   try {
-    if (!res.locals.user || !res.locals.user.is_admin) throw 'Permission denied.';
+    if (!res.locals.user || !res.locals.user.is_admin) throw new ErrorMessage('您没有权限进行此操作。');
 
     let id = parseInt(req.params.id) || 0;
     let tag = await ProblemTag.fromID(id);
@@ -59,7 +59,7 @@ app.post('/problems/tag/:id/edit', async (req, res) => {
     req.body.name = req.body.name.trim();
     if (tag.name !== req.body.name) {
       if (await ProblemTag.findOne({ where: { name: req.body.name } })) {
-        throw 'There is already a tag with that name.';
+        throw new ErrorMessage('标签名称已被使用。');
       }
     }
 
diff --git a/modules/submission.js b/modules/submission.js
index 489f8d7..405e56b 100644
--- a/modules/submission.js
+++ b/modules/submission.js
@@ -71,7 +71,7 @@ app.get('/submissions', async (req, res) => {
 app.get('/submissions/:id/ajax', async (req, res) => {
   try {
     let judge_state = await JudgeState.fromID(req.params.id);
-    if (!judge_state) throw 'No such judge state';
+    if (!judge_state) throw new ErrorMessage('无此提交记录。');
 
     await judge_state.loadRelationships();
 
@@ -162,12 +162,12 @@ app.get('/submission/:id/rejudge', async (req, res) => {
     let id = parseInt(req.params.id);
     let judge = await JudgeState.fromID(id);
 
-    if (judge.pending) throw 'Can\'t rejudge a pending submission';
+    if (judge.pending && !req.query.force) throw new ErrorMessage('无法重新评测一个评测中的提交。');
 
     await judge.loadRelationships();
 
     let allowedRejudge = await judge.problem.isAllowedEditBy(res.locals.user);
-    if (!allowedRejudge) throw 'Permission denied';
+    if (!allowedRejudge) throw new ErrorMessage('您没有权限进行此操作。');
 
     await judge.rejudge();
 
diff --git a/modules/user.js b/modules/user.js
index 565c156..de02e65 100644
--- a/modules/user.js
+++ b/modules/user.js
@@ -43,7 +43,7 @@ app.get('/ranklist', async (req, res) => {
 app.get('/find_user', async (req, res) => {
   try {
     let user = await User.fromName(req.query.nickname);
-    if (!user) throw `Can't find user ${req.query.nickname}`;
+    if (!user) throw new ErrorMessage('无此用户。');
     res.redirect(syzoj.utils.makeUrl(['user', user.id]));
   } catch (e) {
     syzoj.log(e);
@@ -57,7 +57,7 @@ app.get('/find_user', async (req, res) => {
 app.get('/login', async (req, res) => {
   if (res.locals.user) {
     res.render('error', {
-      err: 'Please logout first'
+      err: new ErrorMessage('您已经登录了，请先注销。', { '注销': syzoj.utils.makeUrl(['logout'], { 'url': req.originalUrl }) })
     });
   } else {
     res.render('login');
@@ -68,7 +68,7 @@ app.get('/login', async (req, res) => {
 app.get('/sign_up', async (req, res) => {
   if (res.locals.user) {
     res.render('error', {
-      err: 'Please logout first'
+      err: new ErrorMessage('您已经登录了，请先注销。', { '注销': syzoj.utils.makeUrl(['logout'], { 'url': req.originalUrl }) })
     });
   } else {
     res.render('sign_up');
@@ -109,11 +109,11 @@ app.get('/user/:id/edit', async (req, res) => {
   try {
     let id = parseInt(req.params.id);
     let user = await User.fromID(id);
-    if (!user) throw 'No such user.';
+    if (!user) throw new ErrorMessage('无此用户。');
 
     let allowedEdit = await user.isAllowedEditBy(res.locals.user);
     if (!allowedEdit) {
-      throw 'Permission denied';
+      throw new ErrorMessage('您没有权限进行此操作。');
     }
 
     res.render('user_edit', {
@@ -135,15 +135,15 @@ app.post('/user/:id/edit', async (req, res) => {
     user = await User.fromID(id);
 
     let allowedEdit = await user.isAllowedEditBy(res.locals.user);
-    if (!allowedEdit) throw 'Permission denied.';
+    if (!allowedEdit) throw new ErrorMessage('您没有权限进行此操作。');
 
     if (req.body.old_password && req.body.new_password) {
-      if (user.password !== req.body.old_password && !res.locals.user.is_admin) throw 'Old password wrong.';
+      if (user.password !== req.body.old_password && !res.locals.user.is_admin) throw new ErrorMessage('旧密码错误。');
       user.password = req.body.new_password;
     }
 
     if (res.locals.user.is_admin) {
-      if (!syzoj.utils.isValidUsername(req.body.username)) throw 'Invalid username.';
+      if (!syzoj.utils.isValidUsername(req.body.username)) throw new ErrorMessage('无效的用户名。');
       user.username = req.body.username;
     }
 
@@ -157,12 +157,12 @@ app.post('/user/:id/edit', async (req, res) => {
 
     res.render('user_edit', {
       edited_user: user,
-      error_info: 'Success'
+      error_info: ''
     });
   } catch (e) {
     res.render('user_edit', {
       edited_user: user,
-      error_info: e
+      error_info: e.message
     });
   }
 });
diff --git a/utility.js b/utility.js
index 8ed3a7a..8971c60 100644
--- a/utility.js
+++ b/utility.js
@@ -28,6 +28,14 @@ Array.prototype.filterAsync = async function (fn) {
   return this.filter((x, i) => a[i]);
 };
 
+global.ErrorMessage = class ErrorMessage {
+  constructor(message, nextUrls, details) {
+    this.message = message;
+    this.nextUrls = nextUrls || {};
+    this.details = details;
+  }
+};
+
 let path = require('path');
 let util = require('util');
 let renderer = require('moemark-renderer');
@@ -210,7 +218,7 @@ module.exports = {
     } else {
       let lines = zip.readAsText('data_rule.txt').split('\r').join('').split('\n').filter(x => x.length !== 0);
 
-      if (lines.length < 3) throw 'Invalid data_rule.txt';
+      if (lines.length < 3) throw '无效的数据配置文件（data_rule.txt）。';
 
       let input = lines[lines.length - 2];
       let output = lines[lines.length - 1];
@@ -234,8 +242,8 @@ module.exports = {
             output: output.replace('#', i)
           };
 
-          if (!list.includes(testcase.input)) throw `Can't find file ${testcase.input}`;
-          if (!list.includes(testcase.output)) throw `Can't find file ${testcase.output}`;
+          if (!list.includes(testcase.input)) throw `找不到文件 ${testcase.input}`;
+          if (!list.includes(testcase.output)) throw `找不到文件 ${testcase.output}`;
           res[s].cases.push(testcase);
         }
       }
diff --git a/views/error.ejs b/views/error.ejs
index d0c7faa..9d4fc90 100644
--- a/views/error.ejs
+++ b/views/error.ejs
@@ -1,21 +1,27 @@
 <% this.title = '错误' %>
 <% include header %>
-<style type="text/css">
-    .down{
-    margin-top: 150px;
-    font-size:2em;
-    }
-</style>
-<div class="am-container down">
-    <p><%= err %></p>
-</div>
 
-<% if (typeof next !== 'undefined') { %>
-<script type="text/javascript">
-$(document).ready(function() {
-	setTimeout("window.location.href='<%- next %>'", 2000);
-});
-</script>
-<% } %>
+<%
+if (!(err instanceof ErrorMessage)) {
+  err = new ErrorMessage(err.toString());
+}
+%>
+<div class="ui negative icon message">
+  <i class="remove icon"></i>
+  <div class="content">
+    <div class="header" style="margin-bottom: 10px; ">
+      错误：<%= err.message %>
+    </div>
+    <% if (err.details) { %>
+      <p><%= err.details %></p>
+    <% } %>
+    <p>
+      <% for (let text in err.nextUrls) { %>
+        <a href="<%= err.nextUrls[text] %>" style="margin-right: 5px; "><%= text %></a>
+      <% } %>
+      <a href="javascript:history.go(-1)">返回上一页</a>
+    </p>
+  </div>
+</div>
 
 <% include footer %>
diff --git a/views/problem.ejs b/views/problem.ejs
index eca5c41..cf8bd31 100644
--- a/views/problem.ejs
+++ b/views/problem.ejs
@@ -68,9 +68,9 @@ if (contest) {
           <% } %>
           <% if (user && user.is_admin) { %>
             <% if (problem.is_public) {  %>
-              <button class="small ui button" id="dis_public">取消公开</button>
+              <a class="small ui button" id="dis_public" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'dis_public']) %>">取消公开</a>
             <% } else { %>
-              <button class="small ui button" id="public">公开</button>
+              <a class="small ui button" id="public" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'public']) %>">公开</a>
             <% } %>
           <% } %>
         </div>
@@ -221,31 +221,5 @@ $(function () {
     editor.getSession().setMode("ace/mode/" + $(this).data('mode'));
   });
 });
-<% if (!contest) { %>
-function public_problem() {
-  $.ajax({
-    url: '<%= syzoj.utils.makeUrl(['api', 'problem', problem.id, 'public']) %>',
-    type: 'POST',
-    complete: function () { location.reload(true) },
-    async: true
-  });
-}
-function dis_public_problem() {
-  $.ajax({
-    url: '<%= syzoj.utils.makeUrl(['api', 'problem', problem.id, 'public']) %>',
-    type: 'DELETE',
-    complete: function () { location.reload(true) },
-    async: true
-  });
-}
-$(document).ready(function(){
-  $("#public").click(function(){
-    public_problem();
-  });
-  $("#dis_public").click(function(){
-    dis_public_problem();
-  });
-});
-<% } %>
 </script>
 <% include footer %>
diff --git a/views/problems.ejs b/views/problems.ejs
index bd2e3ce..3c233c5 100644
--- a/views/problems.ejs
+++ b/views/problems.ejs
@@ -69,16 +69,14 @@ if (typeof tags !== 'undefined') tagIDs = tags.map(x => x.id);
             <% } %>
             <a style="margin-left: 10px; " href="<%= syzoj.utils.makeUrl(['problems', 'tag', 0, 'edit']) %>" class="ui labeled icon mini green button"><i class="plus icon"></i> 添加标签</a>
           <% } %>
-          <% if (user) { %>
-            <div style="margin-left: 10px; " class="ui mini buttons">
-              <div class="ui labeled icon mini dropdown button" id="add_problem_dropdown"><i class="plus icon"></i> 添加题目
-              <div class="menu">
-                <a class="item" href="<%= syzoj.utils.makeUrl(['problem', 0, 'edit']) %>"><i class="file icon"></i> 新建题目</a>
-                <a class="item" href="<%= syzoj.utils.makeUrl(['problem', 0, 'import']) %>"><i class="cloud download icon"></i> 导入题目</a>
-              </div>
-              </div>
+          <div style="margin-left: 10px; " class="ui mini buttons">
+            <div class="ui labeled icon mini dropdown button" id="add_problem_dropdown"><i class="plus icon"></i> 添加题目
+            <div class="menu">
+              <a class="item" href="<%= syzoj.utils.makeUrl(['problem', 0, 'edit']) %>"><i class="file icon"></i> 新建题目</a>
+              <a class="item" href="<%= syzoj.utils.makeUrl(['problem', 0, 'import']) %>"><i class="cloud download icon"></i> 导入题目</a>
             </div>
-          <% } %>
+            </div>
+          </div>
         </div>
       </div>
     </div>
diff --git a/views/sign_up.ejs b/views/sign_up.ejs
index 644b69c..8e98d28 100644
--- a/views/sign_up.ejs
+++ b/views/sign_up.ejs
@@ -1,7 +1,7 @@
 <% this.title = '注册' %>
 <% include header %>
-<h1>注册</h1>
 <div class="padding">
+  <h1>注册</h1>
   <div class="ui error message" id="error" data-am-alert hidden>
     <p id="error_info"></p>
   </div>
diff --git a/views/user_edit.ejs b/views/user_edit.ejs
index c03a95c..ca1963c 100644
--- a/views/user_edit.ejs
+++ b/views/user_edit.ejs
@@ -1,9 +1,9 @@
 <% this.title = '修改资料'; %>
 <% include header %>
 <div class="padding">
-    <div class="ui <% if (error_info == 'Success') { %>success<% } else { %>error<% } %> message" id="error" <% if (!error_info) { %>hidden<% } %>>
-      <% if (error_info) {
-          if (error_info == 'Success') error_info = '修改成功';
+    <div class="ui <% if (error_info === '') { %>success<% } else { %>error<% } %> message" id="error" <% if (error_info === null) { %>hidden<% } %>>
+      <% if (error_info !== null) {
+          if (error_info === '') error_info = '修改成功。';
       %>
       	<p id="error_info"><%= error_info %></p>
       <% } %>