how to change base url in drupal 8
sudo nano /etc/apache2/sites-enabled/000-default.conf


Make sure it looks like this:

&lt;VirtualHost *:80&gt;
        # 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 www.example.com

ServerAdmin webmaster@localhost
        ServerName mydomainname.com
        ServerAlias www.mydomainname.com
        DocumentRoot /var/www/html/drupal

&lt;Directory /var/www/html/drupal/&gt;
        Options +FollowSymLinks
        AllowOverride All
        order allow,deny
        allow from all
&lt;/Directory&gt;

        # 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
&lt;/VirtualHost&gt;

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet