如何调试与WordPress建立数据库连接的错误

Question

当我尝试以localhost访问我的WordPress网站时，我得到：

建立数据库连接时出错。

我该如何调试这个问题？ 我能看到哪些日志？

我可以使用localhost上的用户wordpressuser登录MySQL。 我似乎对wordpressuser在数据库wordpress上有正确的授权：

root@myhost# mysql -hlocalhost -uwordpressuser -pmypassword 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 109
Server version: 5.5.37-0+wheezy1 (Debian)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show grants for wordpressuser@localhost;
+----------------------------------------------------------------------------------------------------------------------+
| Grants for wordpressuser@localhost                                                                                   |
+----------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'wordpressuser'@'localhost' IDENTIFIED BY PASSWORD '*somepassword' |
| GRANT ALL PRIVILEGES ON `wordpress`.* TO 'wordpressuser'@'localhost'                                                 |
+----------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

但是当我运行mysqlaccess ，我得到：

root@myhost# mysqlaccess localhost wordpressuser wordpress -pmypassword
mysqlaccess Version 2.06, 20 Dec 2000
By RUG-AIV, by Yves Carlier (Yves.Carlier@rug.ac.be)
Changes by Steve Harvey (sgh@vex.net)
This software comes with ABSOLUTELY NO WARRANTY.
Password for MySQL user wordpressuser: 

Sorry,
An error occured when trying to connect to the database
with the grant-tables:
* Maybe YOU do not have READ-access to this database?
* If you used the -U option, you may have supplied an invalid username?
  for the superuser?
* If you used the -U option, it may be possible you have to supply
  a superuser-password to, with the -P option?
* If you used the -P option, you may have supplied an invalid password?

wget localhost因连接被拒绝而失败：

user@myhost:~$ wget localhost
--2014-06-08 01:11:29--  http://localhost/
Resolving localhost (localhost)... ::1, 127.0.0.1
Connecting to localhost (localhost)|::1|:80... failed: Connection refused.
Connecting to localhost (localhost)|127.0.0.1|:80... connected.
HTTP request sent, awaiting response... 500 Internal Server Error
2014-06-08 01:11:29 ERROR 500: Internal Server Error.

我的wp-config似乎有正确的凭据（DB_NAME，DB_USER，DB_PASSWORD，DB_HOST）。

我该如何调试这个问题？

Answer 1

我设法暂时解决了这个问题如下：

试图找到php访问mysql数据库的地方，我做了一个

grep Ri db.user /var/www

找到那个

/var/www/wp-includes/load.php

在此行中创建数据库：

$wpdb = new wpdb( DB_USER, DB_PASSWORD, DB_NAME, DB_HOST );

我尝试对DB_USER的值进行硬编码。 DB_PASSWORD ， DB_NAME ， DB_HOST ，该站点现在加载在localhost上。 很明显， wp-config.php定义的值与实际传递给new wpdb(...)的值之间存在不匹配，尽管我还没有能够进一步跟踪它。

与其中一条评论中的建议不同：

1. 这不是Web服务器的问题。 该网站现在正常工作，从localhost或外部。

2. 命令wget localhost现在可以正常工作。 它下载了一个包含wordpress设置页面的index.html