Unable to access Magento Due To ERR_EMPTY_RESPONSE

Question

Magento was working fine but then on trying to access http://80.85.85.79/berguard_stationery
I get an error:
This page isn’t working 80.85.85.79 didn’t send any data. ERR_EMPTY_RESPONSE

I have three magento installations on the same server and visiting the urls for all of them brings up the same error.

From the research I have done, I came across this but it wasn't helpful on how to solve the error.

This error is not logged in /var/log/apache2/error.log

Below is my virtualhost file:

<VirtualHost *:80>
    ServerAdmin admin@shop.com
    DocumentRoot /var/www/html
    ServerName shop.com
    ServerAlias shop.com

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

I have edited my virtualhost file to:

<Directory /var/www/html/magento2/magento2-2.3>
    Require all granted
</Directory>
<VirtualHost *:80>
    ServerAdmin admin@shop.com
    DocumentRoot /var/www/html
    ServerName shop.com
    ServerAlias shop.com

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    <Directory /var/www/html/magento2/magento2-2.3>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
</VirtualHost>

I have edited my virtualhost file to:

<VirtualHost *:80>
        # The ServerName directive sets the request scheme, hostname and port that
        # the server uses to identify itself. This is used when creating
        # redirection URLs. In the context of virtual hosts, the ServerName
        # specifies what hostname must appear in the request's Host: header to
        # match this virtual host. For the default virtual host (this file) this
        # value is not decisive as it is used as a last resort host regardless.
        # However, you must set it for any further virtual host explicitly.

        #ServerName shop.com
        #ServerAlias shop.com

        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/html/magento2/magento2-2.3/pub

        # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
        # error, crit, alert, emerg.
        # It is also possible to configure the loglevel for particular
        # modules, e.g.
        #LogLevel info ssl:warn

        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined

        # For most configuration files from conf-available/, which are
        # enabled or disabled at a global level, it is possible to
        # include a line for only one particular virtual host. For example the
        # following line enables the CGI configuration for this host only
        # after it has been globally disabled with "a2disconf".
        #Include conf-available/serve-cgi-bin.conf
        <Directory "/var/www/html">
                AllowOverride all
        </Directory>
</VirtualHost>

I still have the error showing up.

How do I go about solving this error?

Answer 1

As it turns out, for some reason Port 80 on the server was closed. So I reopened Port 80 using;

sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT

Then importantly for the changes to persist even when server is restarted ;

sudo apt-get install iptables-persistent