How to make Apache serve
httpsdocs folder for HTTPS requests?
httpsdocs folder considered as legacy and is kept and created for upgrade case. It will not be created for new domains.
Currently, Plesk is not using
httpsdocs folder and the web server serves both HTTP and HTTPS requests with
httpdocs folder as Document Root by default (can be changed).
In order to customize Document Root for HTTPS only add the following line to Plesk > Domains > example.com > Apache and Nginx Settings > Additional directives for HTTPS:
CONFIG_TEXT: DocumentRoot "/var/www/vhosts/example.com/httpsdocs"