apache2启动报错排查

环境

阿里云ubuntu版本：

LSB Version:    core-11.1.0ubuntu2-noarch:security-11.1.0ubuntu2-noarch
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.1 LTS
Release:        20.04
Codename:       focal

apache:

Server version: Apache/2.4.41 (Ubuntu)
Server built:   2020-08-12T19:46:17

报错

修改apache的配置文件后，重启apache会报错

#service apache2 restart

Job for apache2.service failed because the control process exited with error code.
See "systemctl status apache2.service" and "journalctl -xe" for details.

这个时候不要慌！不要重装！不要放弃！按照提示运行:

systemctl status apache2.service

我这里出现过的错误：

错误1：

● apache2.service - The Apache HTTP Server
     Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Mon 2021-05-31 21:00:24 CST; 3s ago
       Docs: https://httpd.apache.org/docs/2.4/
    Process: 1184602 ExecStart=/usr/sbin/apachectl start (code=exited, status=1/FAILURE)

May 31 21:00:23 iZwz919g91pglb4zkj97ctZ systemd[1]: Starting The Apache HTTP Server...
May 31 21:00:24 iZwz919g91pglb4zkj97ctZ apachectl[1184611]: apache2: Syntax error on line 225 of /etc/apache2/apache2.conf: Syntax error on line 34 of /etc/apach>
May 31 21:00:24 iZwz919g91pglb4zkj97ctZ apachectl[1184602]: Action 'start' failed.
May 31 21:00:24 iZwz919g91pglb4zkj97ctZ apachectl[1184602]: The Apache error log may have more information.
May 31 21:00:24 iZwz919g91pglb4zkj97ctZ systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
May 31 21:00:24 iZwz919g91pglb4zkj97ctZ systemd[1]: apache2.service: Failed with result 'exit-code'.
May 31 21:00:24 iZwz919g91pglb4zkj97ctZ systemd[1]: Failed to start The Apache HTTP Server.

看后面log的第二行：

apache2: Syntax error on line 225 of /etc/apache2/apache2.conf: Syntax error on line 34 of /etc/apach>

进入配置文件中查看34行的错误，具体情况具体分析

错误2：

● apache2.service - The Apache HTTP Server
     Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Mon 2021-05-31 21:04:16 CST; 14s ago
       Docs: https://httpd.apache.org/docs/2.4/
    Process: 1184995 ExecStart=/usr/sbin/apachectl start (code=exited, status=1/FAILURE)

May 31 21:04:16 iZwz919g91pglb4zkj97ctZ systemd[1]: Starting The Apache HTTP Server...
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ apachectl[1185012]: AH00526: Syntax error on line 37 of /etc/apache2/sites-enabled/000-default-ssl.conf:
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ apachectl[1185012]: Invalid command 'ProxyRequests', perhaps misspelled or defined by a module not included in the server>
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ apachectl[1184995]: Action 'start' failed.
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ apachectl[1184995]: The Apache error log may have more information.
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ systemd[1]: apache2.service: Failed with result 'exit-code'.
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ systemd[1]: Failed to start The Apache HTTP Server.

依旧是看log的第二行,这次加上第三行：

May 31 21:04:16 iZwz919g91pglb4zkj97ctZ apachectl[1185012]: AH00526: Syntax error on line 37 of /etc/apache2/sites-enabled/000-default-ssl.conf:
May 31 21:04:16 iZwz919g91pglb4zkj97ctZ apachectl[1185012]: Invalid command 'ProxyRequests', perhaps misspelled or defined by a module not included in the server>

得知ProxyRequests模块未定义，这里是因为我配置了反向代理，然而它找不到模块。只需开启一下代理模块。

运行：