Many common WordPress errors result in a white screen when you visit your app's URL, a problem often referred to as the "white screen of death."
Try these tips to get your WordPress app back to normal.
If only your public-facing site is showing the white screen but you can access the administrative area, log in to your WordPress Dashboard and deactivate all of your plugins. Then, reactivate them one at a time, checking your homepage with each plugin's activation.
If you cannot access your Dashboard, SFTP in to your server as your app's system user and navigate to your plugins folder:
Rename plugins to plugins_old.
This will deactivate all of your plugins, and you should then be able to log in to your WordPress Dashboard and reactivate them one by one.
When you discover the plugin that is causing the white screen to appear, deactivate it again, and let the plugin's author know about the compatibility issues you are experiencing.
If you see the white screen after activating a new theme, log in to your WordPress Dashboard and activate the default WordPress theme.
If you can't access your admin login page, SFTP in to your server as your app's system user and open your themes folder:
Find the folder for the theme that is giving you trouble and rename it to THEMENAME-old.
This should fully deactivate the theme allowing your site to return. You can now contact the theme's author and let him or her know about the compatibility issues.
If you see a white screen after cloning the database on you local development environment, your theme's directory might have accidentally been renamed or deleted. The database contains metadata on themes, and if the actual theme directory isn't found, WordPress may fail to load properly.
To correct this, first log in to your Dashboard at www.YOURDOMAIN.com/wp-admin.
Then, click Visit Site from the WordPress menu in the upper-left corner to view your front end.
It should tell you the theme directory that is failing to load.
SFTP in to your server as your app's system user and open your themes folder:
Check to see if your active theme has been renamed, if it exists at all.
Then, simply uninstall the theme and reinstall it.