diff --git a/framework/base/router.class.php b/framework/base/router.class.php
index 9c61a48c07..e969356383 100644
--- a/framework/base/router.class.php
+++ b/framework/base/router.class.php
@@ -3524,6 +3524,23 @@ class baseRouter
 
         return $installed;
     }
+
+    /**
+     * 检查是否需要升级。如果需要升级并且开启了缓存，清空缓存以避免直接执行 SQL 语句导致数据不一致。
+     * Check if need upgrade. If need upgrade and cache is open, clear the cache to avoid data inconsistency caused by direct execution of SQL statements.
+     *
+     * @access public
+     * @return bool
+     */
+    public function checkNeedUpgrade()
+    {
+        $installedVersion = $this->getInstalledVersion();
+        if($installedVersion == $this->config->version) return false;
+
+        if(!empty($this->cache)) $this->cache->clear();
+
+        return true;
+    }
 }
 
 /**
diff --git a/www/index.php b/www/index.php
index 0cdc609056..97a9fdd47c 100644
--- a/www/index.php
+++ b/www/index.php
@@ -36,8 +36,7 @@ $app = router::createApp('pms', dirname(dirname(__FILE__)), 'router');
 if(!$app->checkInstalled()) die(header('location: install.php'));
 
 /* Check for need upgrade. */
-$config->installedVersion = $app->getInstalledVersion();
-if($config->version != $config->installedVersion) die(header('location: upgrade.php'));
+if($app->checkNeedUpgrade()) die(header('location: upgrade.php'));
 
 /* Run the app. */
 $app->setStartTime($startTime);