How to Debug a WordPress Site That’s Not Working (Blank Screen, 500 Error)
WordPress Debug (Professional Diagnostic Steps)
When WordPress shows a blank screen, throws a 500 error, behaves strangely, or breaks after an update, the fastest way to resolve it is proper debugging: enable logging, check server logs, and isolate whether the issue comes from a plugin or the theme.
1) Enable WordPress debug in wp-config.php
In wp-config.php (above the line “That’s all, stop editing!”) add:
define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);Important: With WP_DEBUG_DISPLAY = false, errors won’t be shown on the screen (safer), but will be written into a log file instead.
2) Check the WordPress debug log
Review the log file:
- wp-content/debug.log
If debug.log is not created, verify that the wp-content folder is writable (write permissions) and that there is an actual PHP error being triggered and logged.
3) Check server Error Logs in cPanel
In parallel, check the server-level errors (these often contain 500/permission/fatal details):
- cPanel → Metrics → Errors
4) Disable all plugins (when you can’t access wp-admin)
Via FTP or File Manager (cPanel), do the following:
- Go to wp-content
- Rename the folder plugins to plugins-disabled
This disables all plugins at once. If the site starts working again, rename the folder back to plugins and re-enable plugins one-by-one to find the problematic one.
5) Switch to a default theme (if the theme is the problem)
If the issue is theme-related and you can’t access WP Admin, you can force WordPress to use a default theme.
Option A (recommended and faster): via files
- Go to wp-content/themes
- Rename the active theme folder (example: mytheme → mytheme-disabled)
WordPress will then try to fall back automatically to an installed default theme (for example: twentytwentyfour).
Option B: via phpMyAdmin (wp_options)
- phpMyAdmin → select the database → open the wp_options table (or your prefix, e.g. abc_options)
- Find the options: template and stylesheet
- Set both values to: twentytwentyfour (or another default theme that actually exists inside wp-content/themes)
Important: The value you enter must match the theme folder name inside wp-content/themes.
6) Security (important)
Don’t debug on a public live site if you can avoid it. If you must debug in production:
- keep WP_DEBUG_DISPLAY = false
- restrict access (maintenance mode, basic auth, IP allowlist, or temporary protection)
- disable debugging immediately after the issue is fixed
