Here is Apache 2 configuration:


# Depends: mpm_prefork
LoadModule mpm_itk_module /usr/lib/apache2/modules/mpm_itk.so


# Conflicts: mpm_event mpm_worker mpm_itk
LoadModule mpm_prefork_module /usr/lib/apache2/modules/mod_mpm_prefork.so

The comments don't add much clarity - mpm-prefork conflicts with mpm-itk, but mpm-itk depends on it?

When /etc/apache2/mods-enabled/mpm_itk.load is removed, there is an error:

AH00534: apache2: Configuration error: No MPM loaded.

I'm not sure what's going on there. Is mpm-itk broken or does it really depend on mpm-prefork?

Is it bad that both modules are loaded? Which of these modules is used by Apache in practice and why? How to make Apache use another one?


You can only use one MPM. So the comment doesn't make any sense. You might consider reporting the problem to the package maintainer.

  • Thanks. Is there a way to know which of MPM modules is in charge at this moment? apache2ctl -M shows both, and there are no errors on module conflict on Apache start. This is production server, so I would prefer to avoid trial and error if possible. – Estus Flask Feb 26 '17 at 18:38
  • @michael-hamptonwhy I thought the same, but why on a working instance sudo apache2ctl -M | grep mpm return mpm_itk_module and mpm_prefork_module. BTW sudo apachectl configtest return Syntax OK. – Pablo A Jan 28 '18 at 16:44

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