Most common WordPress errors and how to fix them
The 10 most common errors, what really causes them and how to fix them. Without panic.
WordPress is robust. It's not perfect. After 20 years of working with WordPress, the errors I see happening are always the same. Ten, maybe fifteen, repeat on every site. Here you'll find what they are, why they happen and how to fix them. No beating around the bush.
1. Critical error: white screen
The classic white screen of death. No error message, no text, just a blank page. Causes: a plugin with a fatal PHP error, exhausted memory, a theme with code incompatible with the PHP version. How to fix: access wp-config.php via FTP, add 'define( "WP_DEBUG", true );' to see the real error. Then rename the suspicious plugin folder in wp-content/plugins to deactivate it. If the site comes back, you've found the culprit.
2. Error 500 Internal Server Error
White page with 'Internal Server Error' or '500' message. Most common cause: corrupted .htaccess file or wrong rules. Second cause: PHP memory limits reached, files too large in the process. How to fix: rename .htaccess to .htaccess.bak and reload. If the site comes back, that was the problem. Recreate the file by going to 'Settings > Permalinks > Save' in the WordPress dashboard. If that's not enough, increase memory_limit in wp-config.php to 256M and see if it changes.
3. 'Error establishing a database connection'
Blunt message, blank page. It means WordPress can't reach the database. Causes: wrong credentials in wp-config.php, deleted database, MySQL user without permissions, MySQL crash. How to fix: check the credentials in wp-config.php, try accessing the database from phpMyAdmin with those same credentials. If you can't get in, contact hosting. If you get in but the database is empty, your hosting has a serious problem. If the error is intermittent, it's almost always overloaded hosting.
4. Update error: 'Briefly unavailable for scheduled maintenance'
Yellow message that appears after an update and won't go away. Cause: WordPress created the .maintenance file during the update and didn't delete it when finished. This happens when the server drops or PHP hangs during the update. How to fix: delete the .maintenance file via FTP. If it's not there, create an empty file then delete it. If the site went into error, check wp-admin. Sometimes you just need to reload.
5. Contact form not sending emails
You fill in the form, press send, everything seems fine but no emails arrive. Causes: the form plugin uses mail() PHP, which on many hosts no longer works. Second cause: SPF/DKIM issues on the domain. Third cause: the email provider blocks because the site is on a blacklisted IP. How to fix: install an SMTP plugin (WP Mail SMTP is the most used), configure it with the credentials of a real mail server. If it still doesn't arrive with SMTP, the problem is DNS (missing or wrong SPF record).
6. Broken layout on mobile but OK on desktop
The site looks normal on a monitor, on smartphones menus overlap, footers are cut off, images go off screen. Causes: the theme lacks CSS breakpoints for mobile, or a plugin added CSS that breaks responsive, or there's a conflict with a page builder (Elementor, WPBakery). How to fix: check with Chrome DevTools in responsive mode, find the element that's breaking things, identify the CSS causing it. If it's a plugin you don't know, deactivate it and see if the layout returns.
7. Plugin that disappears after update
You update a plugin and it stops working. The problem is often a conflict with another plugin or the PHP version. Sometimes the plugin has a dependency on a library that's no longer compatible. How to fix: check the PHP error logs, try downgrading the plugin to the previous version (if you have the zip file), look in the plugin's support section if other users have the same problem. If the conflict is with another plugin, deactivate them one by one until you find the culprit.
8. Slow or unresponsive admin page
The frontend site is fast, but wp-admin is very slow. Saving a page takes 10 seconds, loading the editor even longer. Causes: too many plugins active even if unused, database tables with millions of rows of expired transients, WP-Cron running in the background blocking requests, hosting with insufficient resources. How to fix: deactivate plugins you don't use, clean transients with a plugin like WP-Optimize, replace native WP-Cron with a real cron job on the server.
9. Redirect loop ERR_TOO_MANY_REDIRECTS
The browser says there are too many redirects and the page won't load. Most frequent cause: the site is configured with both HTTP and HTTPS, and one forces a redirect to the other in a loop. Second cause: WordPress settings and .htaccess contradict each other. How to fix: check in wp-config.php that WP_HOME and WP_SITEURL exactly match what you see in the browser (http or https). If you use an SSL plugin, check it's not creating a loop with the hosting settings.
10. Error 403 Forbidden
White page with 'Forbidden' or 'You don't have permission to access'. Cause: file and folder permissions wrong, .htaccess blocks the IP, server mod_security blocks the request. How to fix: permissions must be 755 for folders, 644 for files, 600 for wp-config.php. If they're different, the server refuses access. If permissions are correct, check .htaccess and ask hosting if mod_security is blocking (often happens with AJAX requests from plugins).
If the article made you realize your site has the same problem, email me. Written estimate within 48 hours, €45/h fixed.