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How to Enable HTTP/2 in Apache 2.4 on Ubuntu 18.04


  • A self-managed VPS or dedicated server with Ubuntu 18.04 running Apache 2.4.xx.
  • A registered domain name with working HTTPS (TLS/SSL). HTTP/2 only works alongside HTTPS because most browsers, including Firefox and Chrome, don’t support HTTP/2 in cleartext (non-TLS) mode.

Step 1: Install Apache2

Per default it will be apache2 version 2.4.29 what is enought for http2 support.

  sudo apt install apache2

Step 2: Tell Apache to use PHP FastCGI

You want to make Apache use a compatible PHP implementation by changing mod_php to php-fpm (PHP FastCGI). If your website or app breaks on FastCGI, you can always revert back to mod_php until further troubleshooting.

Install PHP FastCGI module for PHP 7.2, it is default version for Ubuntu 18.04

sudo apt install php7.2-fpm 

Enable required modules, proxy_fcgi and setenvif:

sudo a2enmod proxy_fcgi setenvif

Enable php7.2-fpm:

sudo a2enconf php7.2-fpm 

Disable the mod_php module:

sudo a2dismod php7.2

Restart Apache:

sudo service apache2 restart

Step 3: Change MPM from "prefork" to "event"

Since the default "prefork" MPM (Multi-Processing Module) is not fully compatible with HTTP/2, you’ll need to change Apache’s current MPM to "event" (or "worker"). This is shown by the error message in Apache versions greater than 2.4.27 as – AH10034: The mpm module (prefork.c) is not supported by mod_http2.

Keep in mind that your server requires more horsepower for HTTP/2 than for HTTP/1.1, due to the multiplexing feature and other factors. That said, smaller servers with low traffic may not see much difference in performance.

First, disable the "prefork" MPM:

sudo a2dismod mpm_prefork 

Enable the "event" MPM:

sudo a2enmod mpm_event 

Restart Apache2 and PHP 7.2:

sudo service apache2 restart && sudo service php7.2-fpm restart

Step 4: Add a line to your Virtual Host file

Add the following line to your site’s current Virtual Host config file. This can go anywhere between the ... tags. If you want to serve HTTP/2 for all your sites, add this to your global /etc/apache2/apache2.conf file instead of per each individual site’s Virtual Host file.

Protocols h2 h2c http/1.1

Explanation: h2 is TLS-encrypted HTTP/2, h2c is cleartext HTTP/2, and http/1.1 is ordinary HTTP/1.1.

Having http/1.1 at the end of the line provides a fallback to HTTP/1.1, while h2c is not strictly necessary.

Step 5: Enable the mod_http2 Apache module

Now you can enable the http2 module in Apache:

sudo a2enmod http2

Check Apache2 config and if no errors, restart Apache:

sudo apachectl configtest && sudo service apache2 restart

Step 6 create http2.conf for entire Server HTTP2

Create a new http2.conf

sudo nano /etc/apache2/conf-available/http2.conf

and add all the following rows:

<IfModule http2_module>
    Protocols h2 h2c http/1.1
    H2Direct on

Enable the http2.conf by running

sudo a2enconf http2

Check Apache2 config and if no errors, restart your Apache2

sudo apachectl configtest && sudo service apache2 restart

and enhance your ssl-vhost file (default-ssl.conf):

sudo nano /etc/apache2/sites-available/default-ssl.conf

Amend in your configuration file:

Protocols h2 h2c http/1.1
H2Push on
H2PushPriority * after
H2PushPriority text/css before
H2PushPriority image/jpg after 32
H2PushPriority image/jpeg after 32
H2PushPriority image/png after 32
H2PushPriority application/javascript interleaved

P.S. All in one command (you still have to edit your VirtualHost and ssl config):

sudo apt update
sudo apt upgrade
sudo apt install apache2 php7.2-fpm 
sudo a2enmod proxy_fcgi setenvif
sudo a2enconf php7.2-fpm 
sudo a2dismod php7.2 
sudo service apache2 restart
sudo a2dismod mpm_prefork 
sudo a2enmod mpm_event 
sudo service apache2 restart 
sudo service php7.2-fpm restart
sudo a2enmod http2
sudo service apache2 restart
sudo echo "<IfModule http2_module>" > /etc/apache2/conf-available/http2.conf
sudo echo "Protocols h2 h2c http/1.1" >> /etc/apache2/conf-available/http2.conf
sudo echo "H2Direct on" >> /etc/apache2/conf-available/http2.conf
sudo echo "</IfModule>" >> /etc/apache2/conf-available/http2.conf
sudo a2enconf http2
sudo apachectl configtest && sudo service apache2 restart
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Thanks, It worked for me. Am using apache2 -v 2.4. 29 on ubuntu 18.04.

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Thanks, It worked for me. Am using apache2 -v 2.4. 29 on ubuntu 18.04.

how did you verify if it is working? I mean, how to verify that it's working?

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GAS85 commented Mar 26, 2021

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sudo echo "" > /etc/apache2/conf-available/http2.conf
change to
sudo echo "" >> /etc/apache2/conf-available/http2.conf

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tdanyel commented Nov 18, 2021

In some cases mpm_event may conflict with Ruid2 Module.

your website may goes down and shows ERR_EMPTY_RESPONSE on the browser

If so just disable it and everything may be up again:

$ sudo a2dismod ruid2

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