If username or password is incorrect, wp-login returns the blank page with no header, body or footer. Console shows there are no errors. I have removed my login page building plugin and removed everything from my functions.php, and nothing worked.
The blank page means there's a server error, check the error logs, or add the following line to your wp-config.php file to get them to show on screen.
define( 'WP_DEBUG', true );
That will show you the errors so you can start debugging.
OR
It happens because the theme or plugins that you installed are not supported.
How to check and fix:
Rename the plugin folder name and theme folder name. If opening /wp-admin and entering a valid username and password the dashboard is shown, then it worked.
Revert the folder name of plugin and theme, then activate the themes and plugins one by one, cross-checking with /wp-admin. You will find out the unsupported plugin or theme
