Getting annoyed by the error message displayed each time you forget to use https in your URL when trying to access th Plesk panel?
The “400 Bad Request – The plain HTTP request was sent to HTTPS port” error is caused by a bug in the Parallels Plesk panel version 11.5, here is a quick fix for it:
create a new file called zzz-myhost.conf in /etc/sw-cp-server/conf.d/ and add the following line into it:
error_page 497 https://panel.provider.com:$server_port$request_uri;
(! replace panel.provider.com with your domain/sub-domain or IP address)
Then restart sw-cp-server:
# /etc/init.d/sw-cp-server restart