diff --git a/CHANGELOG.md b/CHANGELOG.md
index a42e2b0..ceb9c26 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,10 +2,8 @@
 
 All notable changes to the "cyezoi" extension will be documented in this file.
 
-## v0.0.28
+## v0.0.29
 
-- **Add count badge and loading icon**
-- Add vote problem solution
-- Fix displaying `{0}` etc
+- Fix contest problem bug
 
 Want to see the previous log? [Click here](https://github.com/CYEZOI/cyezoi-helper/commits/main/CHANGELOG.md)
diff --git a/res/html/problem.js b/res/html/problem.js
index 14b7e33..74704f2 100644
--- a/res/html/problem.js
+++ b/res/html/problem.js
@@ -91,7 +91,7 @@ window.addEventListener('DOMContentLoaded', () => {
                 enableTab('Problem', problemHTML);
                 focusTab('Problem');
 
-                const contestList = data.ctdocs.concat(data.htdocs);
+                const contestList = (data.ctdocs || []).concat(data.htdocs);
                 var relatedHTML = '';
                 if (contestList.length > 0) {
                     contestList.sort((a, b) => new Date(b.beginAt) - new Date(a.beginAt));