我在其中一个托管服务器的joomla下有一个网站。直到昨天它还运行得很好。但从昨天开始，当我打开网站时，它给了我以下错误：
500 - No valid database connection:MySQL server has gone away SQL=SELECT a.*, CASE WHEN CHAR_LENGTH(a.alias) THEN CONCAT_WS(":", a.id, a.alias) ELSE a.id END as slug, CASE WHEN CHAR_LENGTH(cc.alias) THEN CONCAT_WS(":", cc.id, cc.alias) ELSE cc.id END as catslug FROM jos_content AS a INNER JOIN jos_categories AS cc ON cc.id = a.catid INNER JOIN jos_sections AS s ON s.id = a.sectionid WHERE a.state = 1 AND ( a.publish_up = '0000-00-00 00:00:00' OR a.publish_up <= '2012-03-04 17:59:41' ) AND ( a.publish_down = '0000-00-00 00:00:00' OR a.publish_down >= '2012-03-04 17:59:41' ) AND s.id > 0 AND a.access <= 0 AND cc.access <= 0 AND s.access <= 0 AND s.published = 1 AND cc.published = 1 ORDER BY a.created DESC LIMIT 0, 5
或者有时它只是说：
Internal Server Error.
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster@mysite.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
它可能出了什么问题？或者是主办中心出了问题？
将数据库类型从mysql更改为mysqli。