How to Fix Common WordPress Errors (500, White Screen)

Sooner or later every WordPress site shows an error. Most of them have a short list of causes: a plugin or theme conflict, a PHP problem, a server limit or a configuration mistake. The key is to find the cause methodically instead of guessing. Always take a backup before making changes, and work on a staging copy when you can.

Most errors start right after an update or a new plugin, so undo the last change first.
Error logs and WordPress debug mode tell you what is actually wrong.
Deactivating plugins (even without dashboard access) solves a large share of problems.

First steps for any error

What changed? An update, a new plugin, a server move or a settings change is usually the trigger.
Check your email. When a fatal error happens, WordPress often emails the site administrator a link to “recovery mode” that lets you log in with the faulty plugin paused.
Read the error log. Your hosting panel usually has a PHP error log. The message names the file and line where the problem occurred.
Enable debug logging temporarily in wp-config.php: set WP_DEBUG and WP_DEBUG_LOG to true and WP_DEBUG_DISPLAY to false, then read wp-content/debug.log. Turn it off afterwards.

“There has been a critical error on this website”

This message replaced the old “white screen of death”. It means PHP hit a fatal error. Common causes are a plugin or theme incompatible with your PHP or WordPress version.

Use the recovery-mode link from the email, or
Rename the wp-content/plugins folder via SFTP or the file manager to deactivate all plugins. If the site returns, rename it back and reactivate plugins one by one to find the culprit.
If plugins are not the cause, switch to a default theme by renaming your theme’s folder.

500 Internal Server Error

A broken .htaccess file: rename it, then regenerate it by saving Settings → Permalinks.
A PHP fatal error: check the logs, as above.
File permission problems after a migration: files usually 644, folders 755.
Resource limits on shared hosting: check the control panel for CPU, memory or process limits.

“Error establishing a database connection”

Check the database name, user, password and host in wp-config.php; these often change after a migration.
Confirm the database server is running; on shared hosting, ask support or check the status page.
If the message mentions corrupted tables, WordPress has a repair tool you can enable temporarily with WP_ALLOW_REPAIR.

Pages return 404 but the home page works

Go to Settings → Permalinks and click Save without changing anything. This rewrites the rules. On Nginx servers, the server configuration must route requests to WordPress’s index.php; ask your host if saving permalinks does not help.

“Allowed memory size exhausted”

A script needed more memory than PHP allows. Raise the limit with WP_MEMORY_LIMIT in wp-config.php or in the hosting panel’s PHP settings, within your plan’s limits. If one plugin keeps needing more memory, it may be poorly optimised.

Login loops or “cookies are blocked”

Clear browser cookies and cache for the site.
Check that the WordPress Address and Site Address use the same domain and protocol (both HTTPS, same www choice).
Exclude the login and admin pages from caching and CDN rules.

Mixed content and broken styles after moving to HTTPS

Some resources still load over http://. Update the site URLs, search and replace old URLs in the database with a safe tool, and clear all caches.

“Briefly unavailable for scheduled maintenance”

An update was interrupted. Delete the .maintenance file in the WordPress root folder, then run the update again.

Frequently asked questions

How do I deactivate plugins without the dashboard?

Rename the plugins folder, or a single plugin’s folder, through SFTP or your host’s file manager. WordPress deactivates plugins it cannot find.

Is it safe to leave debug mode on?

No. Displaying errors can reveal file paths and other details. Log to a file only while troubleshooting, then disable it.

When should I contact my host?

When errors point to the server: database server down, resource limits, permissions you cannot change, or server configuration such as Nginx rules.