Symptoms of this issue are that when a user attempts to login to the WordPress dashboard, they are redirected by WordPress back to the login page.
Most of the time it happens due to incorrect values for site url and home url fields in WordPress options table. It can also be caused by poorly configured permalink settings or redirects setup in the .htaccess file.
Solutions: a) Clear Cookies to Resolve Login Issues
b) Deactivate All Plugins
c) Revert Back to the Default Theme
d) Update Home URL and SITE URL in wp-config.php