The provided host name is not valid for this server

To solve this problem, just edit '$settings['trusted_host_patterns']' at setting.php file 

This is to configure a list of "trusted" hostnames that the site can run from

If you are running your site from a single hostname "www.example.com", then you should add this to your settings

$settings['trusted_host_patterns'] = array(
  '^www\.example\.com$',
  '^example\.com$',
  );

If you need to run a site of multiple domains and/or subdomains, and are not doing canonical URL redirection, then your setting would look something like this:

$settings['trusted_host_patterns'] = array(
  '^example\.com$',
  '^.+\.example\.com$',
  '^example\.org',
  '^.+\.example\.org',
);

Note: Change the 'example' with your real page name