Unable to start Apache on Ubuntu 16: Failed to mangle name: Invalid argument

Symptoms

• Apache was updated to 2.4.18-2ubuntu3.18 version on Ubuntu 16:

  # dpkg -l | grep apache
  ii apache2 2.4.18-2ubuntu3.18 amd64 Apache HTTP Server
  ii apache2-bin 2.4.18-2ubuntu3.18 amd64 Apache HTTP Server (modules and other binary files)
  ii apache2-data 2.4.18-2ubuntu3.18 all Apache HTTP Server (common files)
  ii apache2-doc 2.4.18-2ubuntu3.18 all Apache HTTP Server (on-site documentation)
  ii apache2-utils 2.4.18-2ubuntu3.18 amd64 Apache HTTP Server (utility programs for web servers)

• Apache is down and can not be started:

  # service apache2 status
  ● apache2.service – LSB: Apache2 web server
  Loaded: loaded (/etc/init.d/apache2; bad; vendor preset: enabled)
  Drop-In: /lib/systemd/system/apache2.service.d
  └─apache2-systemd.conf
  ….
  Dec 02 08:56:52 vnascimento.ubuntu-16.04 apache2[9554]: Invoking ‘systemctl start ‘.
  Dec 02 08:56:52 vnascimento.ubuntu-16.04 apache2[9554]: Use ‘systemctl status ‘ for more info.
  Dec 02 08:56:52 vnascimento.ubuntu-16.04 apache2[9554]: Failed to mangle name: Invalid argument
  Dec 02 08:56:52 vnascimento.ubuntu-16.04 apache2[9554]: Failed to expand names: Invalid argument
  Dec 02 08:56:52 vnascimento.ubuntu-16.04 apache2[9554]: Action ‘start’ failed.

• Sites show 

  502 Bad Gateway

• Unable to repair webserver configuration files for domain:

  # plesk repair web example.com -y
  Error: Can not reconfigure web server configurations: Unable to execute httpdmng: [2020-11-29 18:29:49.780] ERR [util_exec] proc_close() failed [‘/opt/psa/admin/bin/apache_control_adapter’ ‘–restart’ ‘–restart-interval’ ‘0’ ‘–http-port’ ‘7080’ ‘–https-port’ ‘7081’] with exit code [255]
  [2020-11-29 18:29:50.303] ERR [panel] Apache config (16066744630.19908600) generation failed: Template_Exception: Can not restart web server:

Cause

Apache installed from non default repositories causes the issue.

Resolution

1. Connect to the server via SSH.

2. Create backup of /etc/apt/sources.list.

   # cp -p /etc/apt/sources.list /etc/apt/sources.list_bk

3. Remove everything from /etc/apt/sources.list and add below default repository URL’s to this file:

   deb http://archive.ubuntu.com/ubuntu xenial main restricted universe
   deb http://archive.ubuntu.com/ubuntu xenial-updates main restricted universe
   deb http://security.ubuntu.com/ubuntu xenial-security main restricted universe multiverse
   deb http://archive.canonical.com/ubuntu xenial partner

4. Update dependencies:

   # apt-get update

5. Downgrade Apache:

   # apt-get install apache2=2.4.18-2ubuntu3.17 apache2-data=2.4.18-2ubuntu3.17 apache2-bin=2.4.18-2ubuntu3.17 apache2-utils=2.4.18-2ubuntu3.17

6. Install and upgrade packages:

   # apt-get upgrade

7. Restart Apache:

   # service apache2 restart