Common WordPress Errors and Solutions.
“Settings” is a place that should be looked through thoroughly. In here are the settings for your WordPress Application.
Verify all settings are correct. One problem noticed is that at times a site would be installed into a sub directory, such as http://mysite.com/something/, but the General WordPress and site URL settings were set to http://mysite.com/. Which is a conflict. If, by chance you have installed WordPress into a Sub by accident, then you will have to move it to the root.
If your login looks like: http://mysite.com/something/wp-admin/. You have installed in sub.
If otherwise looks like: http://mysite.com/wp-admin/. Then you have installed on root. (correct)
Error 404 after permalink update.
Since you are no longer using a format such as http://mysite.com/?p=123, you will now have 404 errors. This is because ?p=123 no longer exist. It is now a “Pretty Permalink” => /hello-world/. You should setup htaccess redirects for the corresponding posts, since they are bookmarked and shared.
First, backup then rename .htaccess to .htaccess.bac, disable/delete all plugins and themes and set theme to 20** and test. Reinstall core if need be. The system should now be default with no errors, test for error. You can enable your theme and see if error persists. If yes, then may be theme problem, Contact theme Support. If theme is working, then enable plugins one at a time and test. If a problem with the plugin then advise to contact plugin support as well. White Screen of Death WOD may also fall in this.
Change all passwords, scan local environment and don’t worry. Hosts always have a backup. Contact your hosts immediately and advise that your site has been compromised and to install backup for you. If by chance the backup is also infected, then start with following these steps
Most commonly you are trying to login into an area that does not exist. /wp-admin/ always bring up a login screen with a link for “forgot password”. If you do not know your username & email, look in the database under wp_users.
Since php is updated you may want to add the following code to your .htaccess file
AddHandler application/x-httpd-php56 .php