Unable to load theme magento2

If you are one of those who are facing issue "Unable to load theme" while registering a new Magento theme.

You might be experiencing below errors even after creating a new Magento2 theme and properly placing all the necessary files registration.php and theme.xml.
  • 'theme' table in database does not show your theme entry.
  • Content > Design > Theme in admin panel does not show your newly created theme entry.
  • setup:static-content:deploy command stuck while processing your theme.
Well, these all are very frustrating even though the registration.php and theme.xml files are correct.

The issue could be file permission of the theme files. Strange!
  1.  Login as Magento file system owner.
  2. Navigate to Magento2 installation location.
  3. Run below commands.
    chown -R :nginx .   
    (replace 'nginx' by your web server user group name)

    find . -type d -exec chmod 770 {} \; && find . -type f -exec chmod 660 {} \; && chmod u+x bin/magento
More about Magento2 file system permission and ownership at http://devdocs.magento.com/guides/v2.0/install-gde/prereq/file-system-perms.html#install-perms-set

The theme registration issue should be resolved when you access your Magento2 store and run static-content:deploy command. "Unable to load theme" should be gone from console now.