通过覆盖2.25正式版升级到2.26，请问可以直接覆盖？ Nginx出现以下报错： 500 Internal Server Error 删除原来的旧文件后，重新上传： Application error ------ Message: cache_dir "" must be a directory ------ Build: 2.2.6 20130906 PHP Version: 5.2.17 User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.48 Safari/537.36 QQBrowser/7.4.17213.400 ------ exception 'Zend_Cache_Exception' with message 'cache_dir "" must be a directory' in /data/www/ask/system/Zend/Cache.php:197 Stack trace: #0 /data/www/ask/system/Zend/Cache/Backend/File.php(170): Zend_Cache::throwException('cache_dir "" mu...') #1 /data/www/ask/system/Zend/Cache/Backend/File.php(126): Zend_Cache_Backend_File->setCacheDir(false) #2 /data/www/ask/system/Zend/Cache.php(148): Zend_Cache_Backend_File->__construct(Array) #3 /data/www/ask/system/Zend/Cache.php(94): Zend_Cache::_makeBackend('File', Array, false, false) #4 /data/www/ask/system/core/cache.php(73): Zend_Cache::factory('Core', 'File', Array, Array) #5 /data/www/ask/system/functions.inc.php(418): core_cache->__construct() #6 /data/www/ask/system/aws_app.inc.php(270): load_class('core_cache') #7 /data/www/ask/models/account.php(1263): AWS_APP::cache() #8 /data/www/ask/system/aws_controller.inc.php(35): account_class->get_user_group_by_id(99) #9 /data/www/ask/system/aws_app.inc.php(177): AWS_CONTROLLER->__construct() #10 /data/www/ask/system/aws_app.inc.php(49): AWS_APP::create_controller('main', '/data/www/ask.m...') #11 /data/www/ask/index.php(23): AWS_APP::run() #12 {main}