wordpress website crash on https

This is likely caused by insecure content. WordPress is serving resources (images, stylesheets or scripts) over http instead of https.

To resolve this try the following plugins:

Basic SSL setup for WordPress:
https://en-ca.wordpress.org/plugins/really-simple-ssl/

This one will find any internal link/resource request over http and change to https.
https://en-ca.wordpress.org/plugins/ssl-insecure-content-fixer/

error code: 523