403, 500, and White Screen Errors: Understanding and Fixing WordPress Admin Access Issues

Unable to access the WordPress dashboard? White screen, error message, or endless loading? These situations are common… and often stressful.

As a WordPress web agency, we are regularly called upon to restore access after these errors. Here’s an overview of the most frequent messages and our recommendations to resolve them effectively.

Erreur 403 : Accès interdit

Ce que ça signifie :
Le serveur comprend votre demande… mais refuse d’y répondre. Cela peut être lié à un problème de permission ou de sécurité.

Causes fréquentes :

• Fichier .htaccess corrompu ou mal configuré
• Règles de sécurité d’un plugin (comme Wordfence)
• Droits d’accès incorrects sur les fichiers et dossiers
• Adresse IP bloquée par le serveur ou le pare-feu

Solutions :

• Renommer ou supprimer temporairement le fichier .htaccess via FTP, puis en générer un nouveau depuis Réglages > Permaliens
• Désactiver temporairement les plugins de sécurité
• Vérifier les permissions (755 pour les dossiers, 644 pour les fichiers)
• Contacter l’hébergeur si l’IP est blacklistée

Error 500: Internal Server Error

What it means:
The server has encountered an error it cannot process. This error is not specific, which can make diagnosing it tricky.

Common causes:

• Invalid .htaccess file
• Insufficient PHP memory
• Problem in the theme’s functions.php file
• Plugin conflicts

Solutions:

• Delete or recreate the .htaccess file
• Increase PHP memory limit in wp-config.php:
  define('WP_MEMORY_LIMIT', '256M');
• Check the functions.php file as a last resort
• Deactivate all plugins via FTP to test

White Screen of Death

What it means:
Nothing displays. No error, no message—just a blank white page. This is typical of fatal PHP errors.

Common causes:

• Conflict between plugins or theme
• Syntax error in a PHP file
• Insufficient memory

Solutions:

• Enable debug mode in wp-config.php:
  define( 'WP_DEBUG', true );
• Check error_log files
• Switch to a default theme (Twenty Twenty, etc.)
• Deactivate plugins one by one

How We Intervene at Québec WordPress

When we take charge of a locked-out site:

1. We quickly identify the source of the error using server diagnostic tools.
2. We intervene via FTP and the database to restore access to the back office.
3. We fix the root causes (code, plugins, configuration).
4. We implement protections to prevent the issue from recurring.

Our advice: Don’t leave a blocked access unresolved.

An inaccessible WordPress site, even temporarily, can lead to:

• Loss of traffic
• Damage to your reputation with users
• Risk of hacking if the error is related to a security vulnerability

Prevention: Best Practices We Apply

• Regular automatic backups
• Updates tested before deployment
• Monitoring of server errors
• Checking critical files (.htaccess, wp-config.php, etc.)

Is your WordPress site showing one of these errors?
Are you an agency outsourcing the technical side?
Contact our team: we respond quickly to get your site back online and strengthen its stability.