Getting forbidden 403 error only on https but url http working fine

There is some permission related issue in your configuration :

<Directory /var/www/html/wordpress>                    Options Indexes FollowSymLinks MultiViews                    AllowOverride All                    Require all granted</Directory>

it require granted for all files. So all you have to do is make it like :

<Directory "/var/www/html/wordpress">     AllowOverride All</Directory>

P.S. I have modified your file and you use it like :

<IfModule mod_ssl.c><VirtualHost _default_:443>    ServerAlias subdomain.example.com    ServerName subdomain.example.com    DocumentRoot /var/www/html/wordpress<Directory "/var/www/html/wordpress">   AllowOverride All</Directory>    ErrorLog ${APACHE_LOG_DIR}/error.log    CustomLog ${APACHE_LOG_DIR}/access.log combined    SSLEngine on            SSLCertificateFile      /home/ubuntu/wordpress/cdq/my-ssl-certifications/fc1d71b08ac8aab1.crt            SSLCertificateKeyFile /home/ubuntu/wordpress/cdq/my-ssl-certifications/host.key            SSLCertificateChainFile /home/ubuntu/wordpress/cdq/my-ssl-certifications/gd_bundle-g2-g1.crt            <FilesMatch "\.(cgi|shtml|phtml|php)$">                SSLOptions +StdEnvVars            </FilesMatch>            <Directory /usr/lib/cgi-bin>                SSLOptions +StdEnvVars            </Directory>    BrowserMatch "MSIE [2-6]" \                    nokeepalive ssl-unclean-shutdown \                    downgrade-1.0 force-response-1.0    BrowserMatch "MSIE [17-9]" ssl-unclean-shutdown</VirtualHost>

There is no major change. I just modify it according to my working file. Hope it helps you.

Finally resolved the issue. Issue was with the permissions of project folder structure. Now everything is working fine