从ubuntu 14.04 升级ubuntu16.04后，apache2无法启动，如下报错： Starting apache2 (via systemctl): apache2.serviceJob for apache2.service failed because the control process exited with error code. See “systemctl status apache2.service” and “journalctl -xe” for details. failed! 卸载apache2 再次重装仍报错： Job for apache2.service failed … “ubuntu16.04 安装apache2报错 解决方案”