Last Updated on 2017-07-18.

[:en]After updating WP’s plugins, themes or WP itself, sometimes an error 500 appears, especially for multilanguage sites.

Error 500 can have many causes, so first have a look in your Apache log file, e.g. /var/log/apache2/error.log You might encounter a line like this:

AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use ‘LimitInternalRecursion’ to increase the limit if necessary. Use ‘LogLevel debug’ to get a backtrace.

This error is often caused by a wrongly configured .htaccess file in the WP root directory.

Open it and you might see text parts like this one:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /de/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /de/index.php [L]
</IfModule>

# END WordPress

I use the language plugin Qtranslate-X for English and German output. For some reason the .htaccess file is updated in a wrong way:

The RewriteBase must be /, and also the RewriteRule must not contain any language subdirectory etc.

So the corrected lines would be:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

After you have saved the changes, WP should load successfully again.[:]