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Fix “ModSecurity: Output filter: Response body too large” Error on Your WordPress Site

Are you encountering the frustrating “ModSecurity: Output filter: Response body too large” error on your recently migrated WordPress site? You’re not alone! This error can be confusing and disrupt your website’s functionality.

Fortunately, there’s a simple fix. This guide will walk you through the process of resolving this error and getting your website back on track.

Understanding the Error:

When your WordPress site throws this error, it means the size of a specific page exceeds the allowed limit for scanning by ModSecurity, a web application firewall. By default, ModSecurity limits the response body size to 512 KB. If your page content goes beyond this limit, you’ll encounter this error.

Identifying the Problem:

First, you need to locate the error log. If you’re managing the server, look for the file /var/log/apache2/error_log. You can filter the entries by typing:

cat error_log | grep ""

This will display all error entries related to your domain. Look for lines containing the "ModSecurity: Output filter: Response body too large" message.

Fixing the Error:

Here’s how to fix the error:

  1. Increase the SecResponseBodyLimit:

The fix involves increasing the ModSecurity limit for response body size. Open the file /etc/apache2/conf.d/modsec/modsec2.user.conf and add the following line:

SecResponseBodyLimit 1048576

This doubles the default limit to 1048576 bytes (1 MB). You can adjust this value further if necessary.

  1. Increase the SecResponseBodyLimit:

Once you’ve saved the file, restart Apache to apply the changes. You can do this through WHM or by running the command:

service httpd restart

That’s it! The error should now be resolved.

Additional Tips:

  • Double-check your page size: Analyze the affected pages and identify the elements causing the size to exceed the limit. You may need to optimize images, code, or other content to reduce file size.
  • Monitor your website: Keep an eye on your website for any further issues. If the error persists, consult with your hosting provider or a WordPress developer for assistance.

By following these steps, you can easily fix the “ModSecurity: Output filter: Response body too large” error and ensure your WordPress site operates smoothly.