Plesk web server reconfiguration fails on Debian/Ubuntu with Plesk: Curl failed: Timeout was reached

Symptoms

Note: this article is applicable only to Ubuntu and Debian.

• It is not possible to manage Apache service in Tools & Settings > Services Management with the following error:

  PLESK_ERROR: Error: Unable to make action: Unable to manage service by apache_control_adapter: ('start', 'web'). Error:

• Manual webserver reconfiguration fails with the following error:

  # /usr/local/psa/admin/bin/httpdmng --reconfigure-all
  Curl failed: Timeout was reached
  Error occured while sending feedback. HTTP code returned: 500
  Execution failed.
  ...
  Curl failed: Timeout was reached
  ERR [panel] Apache config (15081436330.64775600) generation failed: Template_Exception: Can not restart web server:
  file: /opt/psa/admin/plib/Service/Driver/Web/Server/Apache.php
  line: 109
  code: 0
  Curl failed: Timeout was reached
  Can not restart web server:

• The following error can be found in the /var/log/apache2/error.log file:

  # less /var/log/apache2/error.log
  ...
  [wsgi:crit] [pid 28156] mod_wsgi (pid=28156): The mod_python module can not be used on conjunction with mod_wsgi 4.0+. Remove the mod_python module from the Apache configuration.
  AH00016: Configuration Failed
  ...

• The packages libapache2-mod-wsgi and libapache2-mod-python are installed:

  # dpkg -l | grep libapache2-mod-
  ...
  ii libapache2-mod-python 3.3.1-11ubuntu2 amd64 Python-embedding module for Apache 2
  ii libapache2-mod-wsgi 4.3.0-1.1build1 amd64 Python WSGI adapter module for Apache
  ...

• Also, apache2 service appears as inactive (dead)

Cause

mod_python and mod_wsgi Apache modules are enabled at the same time.

Resolution

1. Connect to the server using SSH 
2. Disable "mod_python" in /etc/apache2/mods-available/python.load by commenting or removing the following string using 'vi' editor:

   CONFIG_TEXT: LoadModule python_module /usr/lib/apache2/modules/mod_python.so

   Note: This module may be loaded in other file, use grep command to find it.

3. Restart Apache:

   # service apache2 restart