Solved: HTTP ERROR 500 example.com currently unable to handle thisrequest.

Problem:-
example.com currently unable to handle this request. HTTP ERROR 500
Solution:-
Above error is general  and can be related to multiple things. Here we will look at a step by step approach to troubleshoot this. Login to your linux server.(If it’s AWS instance refer How to login to AWS EC2 Linux Instance )

1. First identify if you have recently made changes in any of the files related to the site.
2. Go to apache2/logs directory in your server and check error_log to see if it point to any obvious issue. If you are using wordpress bitnami image you will find logs in /opt/bitnami/apache2/logs/error_log or for others you can find logs in /var/apache2/logs/ .
3. If not clear from logs than see if any plugins are conflicting with each other after installation or upgrade. To eliminate this rename your wp-content/plugins to wp-content/plugins-old. You can find this directory in bitnami image at path /opt/bitnami/apps/wordpress/htdocs/wp-content. If you are  able to reach your website after doing this than well done!. Rename wp-content/plugins-old  back to wp-content/plugins. Now try renaming the plugins directories inside wp-content/plugins one by one to find the problem plugin. You can also  try disabling the plugins one by one from your site if you got admin access now,  to find the faulty plugin. If it still doesn’t help than go to step 4.
4. Check if the problem is with installed themes. For this rename wp-content/themes directory to wp-content/themes-old and try to access the site now. If this help change the theme.
5. Check if any changes are made to antivirus or firewall.
6. Sometime the problem can also be with file permissions, like check that wp-config.php has correct permissions. Generally it works fine with 664 permission. Try changing to that. In linux you can do this with chmod.

chmod 664 wp-config.php

Hope the above steps helps you in fixing the issue.