HTTP/2 configuration not running after mod_http2 enabled and protocols set in conf file [duplicate]

Question

HTTP/2 does not seem to be running after what seems to be a proper installation.

I am running CentOS 7.

I installed the latest version of Apache, version httpd-2.4.35-5.el7.x86_64, and have been trying to get HTTP/2 working.

For this, I see that we need to have http2_module running. That is active and running. I believe to have confirmed this by running the command httpd -M. http2_module (shared) is listed under those modules.

The next thing I know to do is add in Protocols h2 h2c http/1.1 above the <VirtualHost ...> tag. I have done that as well.

Finally, I have CURLed my URL, and I am still getting HTTP/1.1.
CURL command: curl -vsko /dev/null --http2 https://www.thehomepainter.com

Brief response from the CURL:

GET / HTTP/1.1 Host: www.thehomepainter.com User-Agent: curl/7.64.0 Accept: /

< HTTP/1.1 200 OK

Partial from httpd.conf

Protocols h2 h2c http/1.1
<VirtualHost *:443>
    SSLEngine on
    ServerAdmin ### omitted ###
    ServerName thehomepainter.com
    ServerAlias www.thehomepainter.com
    DocumentRoot /var/www/html/
    Options -Indexes

    ProxyRequests off
    ProxyPreserveHost On
    AllowEncodedSlashes NoDecode

    ProxyPass "/" "http://localhost:3000/"
    ProxyPassReverse "/" "http://localhost:3000/"

    RequestHeader set X-Forwarded-Proto "https"
    RequestHeader set X-Forwarded-Port "443"

    Include /etc/letsencrypt/options-ssl-apache.conf
    SSLCertificateFile ### omitted ###
    SSLCertificateKeyFile ### omitted ###
    SSLCertificateChainFile ### omitted ###

    # i have tried this here as well
    # Protocols h2 h2c http/1.1
</VirtualHost>

Protocols h2 h2c http/1.1
<VirtualHost *:80>
    ServerAdmin [email protected]
    ServerName thehomepainter.com
    ServerAlias www.thehomepainter.com
    DocumentRoot /var/www/html
    RewriteEngine on
    RewriteCond %{SERVER_NAME} =thehomepainter.com [OR]
    RewriteCond %{SERVER_NAME} =www.thehomepainter.com
    RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]

    # i have tried this here as well
    # Protocols h2 h2c http/1.1
</VirtualHost>

So the expected result is for HTTP/2 to work. However, it is not and I have no idea why.

Answer 1

After scraping through the error log I finally found the issue.

[http2:warn] [pid 7155] AH10034: The mpm module (prefork.c) is not supported by mod_http2. The mpm determines how things are processed in your server. HTTP/2 has more demands in this regard and the currently selected mpm will just not do. This is an advisory warning. Your server will continue to work, but the HTTP/2 protocol will be inactive.

To solve, I edited /etc/httpd/conf.modules.d/00-mpm.conf

Comment out this line: LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

And uncomment the bottom line: LoadModule mpm_event_module modules/mod_mpm_event.so

Restart apache and then it works.