To debug WordPress many sites will tell you to add the WP_DEBUG setting on its own to your wp-config.php file, but this can be quite harmful as many server configurations will start showing PHP errors and warning messages on your site pages. Most sites will also log any errors to some form or error log, but this isn't always the best place for them to go.
It is possible to add a set of debug options that will allow WordPress to log any errors or warnings to a file. Open up your wp-config.php file and add the following lines of code above the line that says "/* That's all, stop editing! Happy blogging. */". Any changes to this file should always go above this line so that you can keep track of them.