I’m using wordpress. One day I have encountered this problem. I can access every page in my blog except /wp-admin.
The error said that there were too many redirects and error 500.
Many searches requested me to change the configuration in wp-config and modify that as SSL redirect as true/false. But that didn’t work. Finally I found that I can access wp-admin using: https://www.example.com/wp-admin/index.php
Try this format this will work.
If you want to make https://www.example.com/wp-admin work then simply modify in .htacess or nginx.conf