Ubuntu20.4启用php53模块后Apache2启动失败求助

通过ppa:sergey-dryabzhinsky/php53安装PHP5.3，安装Apache2后执行sudo a2enmod php53，提示需重启Apache2，但执行sudo systemctl restart apache2后服务器停止且无法启动。

系统日志（journalctl -xe）输出 #

The job identifier is 5493.
Mar 06 13:49:01 ip-172-31-39-129 apachectl[10817]: [Wed Mar 06 13:49:01.199228 2024] [:crit] [pid 10817:tid 140524561787968] Apache is running a threaded M>
Mar 06 13:49:01 ip-172-31-39-129 apachectl[10817]: AH00013: Pre-configuration failed
Mar 06 13:49:01 ip-172-31-39-129 apachectl[10814]: Action 'start' failed.
Mar 06 13:49:01 ip-172-31-39-129 apachectl[10814]: The Apache error log may have more information.
Mar 06 13:49:01 ip-172-31-39-129 systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
-- Subject: Unit process exited
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- An ExecStart= process belonging to unit apache2.service has exited.
--
-- The process' exit code is 'exited' and its exit status is 1.
Mar 06 13:49:01 ip-172-31-39-129 sudo[10806]: pam_unix(sudo:session): session closed for user root
Mar 06 13:49:01 ip-172-31-39-129 systemd[1]: apache2.service: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- The unit apache2.service has entered the 'failed' state with result 'exit-code'.
Mar 06 13:49:01 ip-172-31-39-129 systemd[1]: Failed to start The Apache HTTP Server.
-- Subject: A start job for unit apache2.service has failed
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
--
-- A start job for unit apache2.service has finished with a failure.
--
-- The job identifier is 5493 and the job result is failed.

Apache2错误日志输出 #

[Wed Mar 06 13:48:07.632271 2024] [mpm_event:notice] [pid 10483:tid 140403607956544] AH00489: Apache/2.4.41 (Ubuntu) configured -- resuming normal operations
[Wed Mar 06 13:48:07.632364 2024] [core:notice] [pid 10483:tid 140403607956544] AH00094: Command line: '/usr/sbin/apache2'
[Wed Mar 06 13:49:01.156933 2024] [mpm_event:notice] [pid 10483:tid 140403607956544] AH00491: caught SIGTERM, shutting down

补充说明：已安装mysql-server、php53、libapache2-mod-php53、php53-xml、php53-mbstring，因无可用包未安装php53-mysql。

关键报错Apache is running a threaded MPM指向核心问题：PHP5.3的Apache模块libapache2-mod-php53仅支持非线程化的prefork MPM，而当前Apache默认启用的是线程化的event MPM，两者不兼容，导致启动失败。

• 切换Apache的MPM为prefork
  先禁用当前的event MPM：

  sudo a2dismod mpm_event
  

  启用prefork MPM：

  sudo a2enmod mpm_prefork
  

• 确保PHP5.3模块已启用
  重新执行启用命令，避免状态异常：

  sudo a2enmod php53
  

• 重启Apache服务

  sudo systemctl restart apache2
  

• 验证服务状态
  执行命令确认服务运行状态：

  sudo systemctl status apache2
  

  也可以在/var/www/html/目录下创建info.php文件，内容如下：

  <?php phpinfo(); ?>
  

  通过浏览器访问该文件，检查PHP5.3是否正常加载。

内容的提问来源于stack exchange，提问作者Nichm