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Troubleshooting 'The response is not a valid JSON response' in Solid Security

40 threads Sep 10, 2025

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If you're encountering the frustrating "The response is not a valid JSON response" error while trying to save settings or complete the setup wizard for the Solid Security plugin, you're not alone. This is a common issue that can prevent you from configuring this essential security tool. This guide will explain why this error occurs and provide the most effective solutions to resolve it.

Why This Error Occurs

This error is almost always related to how the plugin communicates with your WordPress site's REST API. The Solid Security plugin relies heavily on the REST API to save settings and complete its setup wizard. The error appears when the plugin sends a request to the server but receives an invalid or unexpected response, often due to a server-level configuration blocking the necessary communication methods.

Common Solutions

Based on community reports and successful resolutions, here are the most effective steps to fix this issue.

1. Enable All HTTP Methods on Your Server

This is the most common and successful fix. The Solid Security plugin requires that all REST HTTP methods—specifically GET, POST, PUT, PATCH, DELETE, and OPTIONS—are enabled on your server. Sometimes, hosting providers or security configurations disable some of these methods.

How to fix it: You will need to contact your hosting provider's support team. Request that they "enable all HTTP methods for the WordPress REST API." They will know how to adjust the server configuration (e.g., in the .htaccess file for Apache or server block config for Nginx) to allow these requests. After they confirm the change, clear your browser cache and try the Solid Security setup again.

2. Check for SSL/HTTPS Configuration Issues

Incorrect SSL configuration, particularly with services like Cloudflare, can interrupt the secure communication between your browser and the server, leading to invalid responses.

How to fix it: If you use Cloudflare, ensure your SSL/TLS encryption mode is set to "Full" instead of "Flexible." Flexible mode can sometimes cause mixed-content issues that break API requests.

3. Investigate with Browser Developer Tools

For a more technical diagnosis, you can use your browser's developer tools to see the exact network request that is failing.

How to do it:

  1. Open your browser's developer tools (usually by pressing F12).
  2. Navigate to the Network tab.
  3. Reproduce the error by clicking "Save" in the Solid Security settings.
  4. Look for any POST requests (often to a URL containing wp-json) that have a red status code (like 403 or 405). Clicking on these failed requests can provide detailed error information that you can then provide to your hosting provider for further investigation.

What Doesn't Usually Cause This Error

It's helpful to know what is likely not the root cause, based on common troubleshooting:

  • Theme or Plugin Conflicts: While always a possibility, users have reported this error persists even with all other plugins disabled and a default WordPress theme active.
  • File Permissions: This error is related to server communication, not file writability.

Conclusion

The "not a valid JSON response" error in Solid Security is predominantly a server configuration issue. The most reliable solution is to contact your hosting provider to ensure all necessary HTTP methods are enabled for the WordPress REST API. Once this server-level block is removed, the plugin's setup and settings pages should function normally, allowing you to secure your website without interruption.

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