diff --git a/db/app_uoj233.sql b/db/app_uoj233.sql
index 806f345..1d2c42f 100644
--- a/db/app_uoj233.sql
+++ b/db/app_uoj233.sql
@@ -995,7 +995,8 @@ INSERT INTO `upgrades` (`name`, `status`, `updated_at`) VALUES
   ('21_problem_difficulty', 'up', now()),
   ('28_remote_judge', 'up', now()),
   ('31_problem_resources', 'up', now()),
-  ('36_decimal_score_range', 'up', now());
+  ('36_decimal_score_range', 'up', now()),
+  ('40_contest_resources', 'up', now());
 /*!40000 ALTER TABLE `upgrades` ENABLE KEYS */;
 UNLOCK TABLES;
 
diff --git a/web/app/upgrade/40_contest_resources/up.sql b/web/app/upgrade/40_contest_resources/up.sql
new file mode 100644
index 0000000..760bfc3
--- /dev/null
+++ b/web/app/upgrade/40_contest_resources/up.sql
@@ -0,0 +1 @@
+ALTER TABLE `contests` MODIFY `extra_config` json NOT NULL;
diff --git a/web/app/upgrade/40_contest_resources/upgrade.php b/web/app/upgrade/40_contest_resources/upgrade.php
new file mode 100644
index 0000000..6d51321
--- /dev/null
+++ b/web/app/upgrade/40_contest_resources/upgrade.php
@@ -0,0 +1,37 @@
+<?php
+return function ($type) {
+	if ($type == 'up_after_sql') {
+		DB::init();
+
+		$contests = DB::selectAll("select * from contests");
+
+		foreach ($contests as $contest) {
+			$extra_config = json_decode($contest['extra_config'], true);
+
+			if (isset($extra_config['links'])) {
+				$new_links = [];
+
+				foreach ($extra_config['links'] as $link) {
+					if (isset($link['name'])) continue;
+
+					$new_links[] = [
+						'name' => $link[0],
+						'url' => '/blogs/' . $link[1],
+					];
+				}
+
+				$extra_config['links'] = $new_links;
+			}
+
+			DB::update([
+				"update contests",
+				"set", [
+					"extra_config" => json_encode($extra_config, JSON_FORCE_OBJECT),
+				],
+				"where", [
+					"id" => $contest['id'],
+				],
+			]);
+		}
+	}
+};