This error usually results into a plain white screen with no error message. This makes it the most puzzling because you have no clue where to look and what to fix.
Most of the time it is caused when a script exhausts PHP memory limit. It can also happen due to a configuration on the server.
WordPress debug function
You can use the WordPress debug function to see what type of errors are being outputted. Add the following code in your wp-config.php file
error_reporting(E_ALL); ini_set('display_errors', 1);
define( ‘WP_DEBUG’, true);
Once you add this, the blank screen will now have errors, warnings, and notices. These may be able to help you determine the root cause.
Increasing the Memory Limit
you need to paste this code in wp-config.php file just before the line that says ‘That’s all, stop editing! Happy blogging.’
define( 'WP_MEMORY_LIMIT', '256M' );
Disabling All Plugins
Inside wp-content folder, you will see a folder called plugins. This is where WordPress stores all plugins installed on your website.
Right click on the plugins folder and select Rename. Change the name of the plugins folder to anything that you like.Once you do this, all of your plugins will be deactivated.
Replace Theme with a Default Theme
If the plugin troubleshooting doesn’t fix the issue, then you should try replacing your current theme with a default twenty ten theme. The best way to do this is by backing up your theme folder. Then deleting the theme. WordPress will automatically fall back to the default theme.