Zend certified PHP/Magento developer

ERR_SSL_PROTOCOL_ERROR on ubuntu apache2

Trying the configure SSL on Apache2 on Ubuntu server installed Apache

sudo apt install apache2
Opened ufw firewall
sudo ufw allow 'Apache'
ufw allow https

Installed SSL files in /root/cert

chmod 400 /root/cert/*
  chmod 500 /root/cert/

In /etc/apache2/sites-available found two conf files: domainname.conf and default-ssl.conf.wordpress.conf Did not know which one to modify, so modified domainname.conf by adding following lines

<VirtualHost *:80>
ServerName www.domainname.com
   ServerAdmin info@domainname.com
DocumentRoot /var/www/domainname
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
<VirtualHost *:443>
    ServerName www.domainname.com
   ServerAdmin info@domainname.com
DocumentRoot /var/www/domainname
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined        # SSL
    SSLEngine on
SSLCertificateFile /root/cert/domain.crt
    SSLCertificateKeyFile /root/cert/domain.key
    SSLCertificateChainFile /root/cert/ca_bundle.crt
 </VirtualHost>

wordpress.conf has following entries:

<VirtualHost *:80>
 DocumentRoot /srv/www/wordpress
 <Directory /srv/www/wordpress>
   Options FollowSymLinks
   AllowOverride Limit Options FileInfo
   DirectoryIndex index.php
   Require all granted
 </Directory>
 <Directory /srv/www/wordpress/wp-content>
   Options FollowSymLinks
   Require all granted
 </Directory>
</VirtualHost>
<VirtualHost *:443>
 DocumentRoot /srv/www/wordpress
 <Directory /srv/www/wordpress>
   Options FollowSymLinks
   AllowOverride Limit Options FileInfo
   DirectoryIndex index.php
   Require all granted
 </Directory>
 <Directory /srv/www/wordpress/wp-content>
   Options FollowSymLinks
   Require all granted
 </Directory>
</VirtualHost>

I check if SSL is running

netstat -ntlp |  grep 443
tcp6       0      0 :::443                  :::*                    LISTEN      961/apache2 

when I perform http://localhost the website comes up. However when I perform https://localhost then it gives error ERR_SSL_PROTOCOL_ERROR. The website is wordpress based and there is a directory /srv/www/wordpress/ and there are several php files. This was created by another person and I don’t know if something needs to be edited in there for SSL.

Can someone tell me how to fix it?