mjhjmtu

Today, I ran an upgrade as every week of my Debian web server.

I was greeted with message:

apache2 (2.4.25-3+deb9u5) stretch; urgency=medium
 * This package upgrades mod_http2 to the version from apache2 2.4.33. This
 fixes a lot of bugs and some security issues, but it also removes the
 support for using HTTP/2 when running with mpm_prefork. HTTP/2 support
 is only provided when running with mpm_event or mpm_worker.
-- Stefan Fritsch <sf@debian.org> Sat, 02 Jun 2018 09:51:46 +0200

Which surprised me, because I use HTTP/2 on my server. I tested my server on SSL Labs, and really the HTTP/2 is gone.

How do I remedy it supposing I use the official Apache and PHP 7.0 packages?

In my case I applied the following as root to get it running again:

# Stop Apache2 web server.
apachectl stop

# If you don't have fpm already installed.
apt-get install php7.0-fpm

# Enable some mods.
a2enmod proxy_fcgi setenvif

# Enable php7.0-fpm configuration.
a2enconf php7.0-fpm

# Disable php7.0 mod.
a2dismod php7.0

# Disable the prefork MPM. Only one MPM can run at a time.
a2dismod mpm_prefork

# Enable event MPM. You could also enable mpm_worker.
a2enmod mpm_event

# Start Apache2 web server.
apachectl start

I hope I did not forget something. Feel free to comment.