500 - Internal Server Error

What does the 500 Internal Server Error mean?

The HTTP status code 500 (Internal Server Error) is a general error message from the web server. It indicates that an unexpected problem has occurred whilst processing a request - the server cannot successfully complete the request without a more specific error code being applicable.

Unlike errors such as 404 (Page Not Found) or 403 (Access Denied), the 500 error does not provide any direct indication of the cause. Systematic troubleshooting is therefore required.

Important: The 500 error is a server-side error. The problem does not lie with the visitor’s browser or device, but rather with the server configuration, the application code or a resource limitation.

Common causes of the 500 error

There are many possible causes of a 500 Internal Server Error. Here are the most common triggers:

Step 1: Analyse the error log

The first and most important step in troubleshooting is to analyse the error log. This is where the server records detailed information about every error.

How to find the error log

Your domain’s error log is located at:

/home/users/IHR-BENUTZERNAME/logs/ihre-domain.de/error.log

Access options:

• KeyHelp File Manager: General → File Manager → logs → your-domain.de
• FTP/SFTP: Navigate to the directory logs in your home directory
• SSH: tail -100 ~/logs/ihre-domain.de/error.log

Typical error messages in the error log

→ Detailed guide: Reading and understanding server log files

Step 2: Troubleshoot common causes

Incorrect .htaccess file

The .htaccess file is one of the most common causes of 500 errors. A single typo can bring the entire website to a standstill.

How to check the .htaccess file:

1. Temporarily rename the .htaccess file: .htaccess → .htaccess_backup
2. Reload the website
3. Is the page working? If so, the error is in the .htaccess file
4. Check the file line by line for errors

Common .htaccess errors:

• Typing errors in directives (e.g. RewriteRul instead of RewriteRule)
• Missing RewriteEngine On before RewriteRules
• Invalid syntax in regular expressions
• Obsolete directives that are no longer supported in newer versions of Apache
• Unclosed <IfModule>blocks

WordPress default .htaccess:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

Fixing PHP errors

PHP errors are the second most common cause. Here’s what to do:

1. Check the error log for PHP error messages
2. Make a note of the affected file and line number
3. Correct the error or restore the last working backup

For WordPress: Plugins or themes are often to blame. Rename the plugin folder to deactivate all plugins:

/www/wp-content/plugins → /www/wp-content/plugins_deaktiviert

Correct file permissions

Incorrect file permissions can prevent the web server from reading or executing files.

Recommended permissions:

Correct all permissions via SSH:

# Alle Verzeichnisse auf 755 setzen
find /www -type d -exec chmod 755 {} \;

# Alle Dateien auf 644 setzen
find /www -type f -exec chmod 644 {} \;

Increase the PHP memory limit

If the error log Allowed memory size exhausted shows that your script requires more memory.

Solution 1: Via php.ini (recommended)

Create or edit a php.ini in the root directory of your domain:

memory_limit = 256M

Solution 2: Via .htaccess

php_value memory_limit 256M

Solution 3: In the PHP script

<?php
ini_set('memory_limit', '256M');
?>

Note: Your hosting package determines the maximum storage limit. With SpeedIT, you can adjust the limit in KeyHelp under Domains → PHP Settings.

Step 3: WordPress-specific solutions

There are a few typical scenarios for WordPress websites:

Identifying a faulty plugin

1. Connect to the server via FTP/SFTP
2. Navigate to /www/wp-content/
3. Rename the pluginsfolder to plugins_old
4. Reload the webpage - does it work now?
5. Create a new, empty pluginsfolder
6. Move the plugins back one by one and test after each one
7. The plugin after which the error reoccurs is the culprit

Identify the faulty theme

1. Rename your active theme (under /www/wp-content/themes/)
2. WordPress will automatically switch to a default theme (e.g. Twenty Twenty-Four)
3. Does the site work? If so, the theme is faulty

Enable WordPress debug mode

To obtain more detailed error messages, enable debug mode in the wp-config.php:

// Debug-Modus aktivieren
define('WP_DEBUG', true);

// Fehler in Datei statt auf Bildschirm ausgeben
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);

// Skript-Debug für CSS/JS
define('SCRIPT_DEBUG', true);

The debug information is stored in /www/wp-content/debug.log .

Important: Remember to deactivate debug mode on live sites once you’ve finished troubleshooting!

Step 4: Advanced diagnostics

Check for ModSecurity blocking

Sometimes the Web Application Firewall (ModSecurity) blocks legitimate requests and causes a 500 error (or 403).

Signs of ModSecurity blocking:

• The error only occurs during certain actions (e.g. submitting a form, saving an item)
• In the error log, you will find entries containing [security2:error] or ModSecurity

How to identify ModSecurity blocks:

grep "ModSecurity" ~/logs/ihre-domain.de/error.log

→ Detailed guide: ModSecurity - your shield against cyber attacks

Check the PHP version

Some applications are not compatible with all PHP versions. Updating or downgrading the PHP version may help.

Change the PHP version:

1. Log in to the web server control panel
2. Navigate to Domains
3. Select the domain and change the PHP version

Compatibility overview:

Check the database connection

If the database connection fails, this may result in a 500 error.

Check:

• Are the login details in the configuration file (e.g. wp-config.php) correct?
• Does the database still exist? (Check in KeyHelp under Resources → Databases)
• Does the database user have the necessary permissions?

Quick troubleshooting checklist

Work through this checklist systematically:

When should you contact support?

We recommend contacting our support team in the following cases:

• The error log does not contain any meaningful error messages
• The error occurs on the server side (not in the application code)
• You suspect there is a problem with the server configuration
• ModSecurity is blocking legitimate requests and you need an exception rule
• The error occurs suddenly, without you having made any changes

Please include the following in your support enquiry:

• Affected domain
• When the error first occurred
• What actions you have already taken
• The relevant lines from the error log

Related articles

• Reading and understanding server log files
• ModSecurity - your shield against cyber attacks
• Server unreachable / IP block
• 404 Not Found - Page not found

Need help?

If you are unable to resolve the issue yourself, please contact our support team. We’ll be happy to help - including via remote support.

Contact support