How to Fix HTTP 406 Not Acceptable Error?

The developers can resolve this by implementing proper content negotiation on the server side and ensuring correct MIME type configurations. If you are a website visitor, switching browsers or disabling browser extensions usually solves the problem. The most 406 errors can be fixed in minutes with these basic troubleshooting steps.

What is the HTTP 406 Not Acceptable Error?

The HTTP 406 Not Acceptable Error occurs when a web server cannot deliver content that matches the client’s accepted content types. This error appears when your browser requests specific content formats through the Accept header, but the server cannot provide those formats. For example, if your browser asks for JSON data, but the server can only send XML, you’ll see a 406 error.

Common causes include incorrect Accept headers, server misconfiguration, or content negotiation issues. To fix this, check your request headers, update content type settings, or modify server configurations to support the requested format.

Common Causes of HTTP 406 Errors

Before fixing the issue, identify the root cause:

How to Fix HTTP 406 Not Acceptable Error (A Step-by-Step Solutions)

Fix 1: Check the Accept Header (Client-Side)

The client (browser, API tool) must request a supported format.

Steps:

Inspect Headers (Chrome DevTools):

Accept: application/json

Test with Curl/Postman:

curl -H "Accept: application/json" https://api.example.com/data

curl -H "Accept: application/xml" https://api.example.com/data

Fix 2: Configure Server MIME Types

If the server doesn’t support the requested format, adjust its MIME types.

For Apache (.htaccess)

AddType application/json .json
AddType application/xml .xml

For Nginx (mime.types)

Ensure JSON/XML are listed:

Restart the server afterward.

Fix 3: Debug Framework-Specific Issues

Django Fix

If Django returns 406, check:

REST_FRAMEWORK = {
    'DEFAULT_RENDERER_CLASSES': [
        'rest_framework.renderers.JSONRenderer',
        'rest_framework.renderers.BrowsableAPIRenderer',
    ]
}

@api_view(['GET'])
@renderer_classes([JSONRenderer])
def my_api(request):
    return Response({"data": "example"})

WordPress Fix

Fix 4: Test API with Postman/Swagger

4. Advanced Troubleshooting to Resolve HTTP 406 Not Acceptable Error?

Check Server Logs

"406 Not Acceptable: Supported formats: json, xml"

Proxy/CDN Conflicts

How to Prevent HTTP 406 Not Acceptable Error in Future

Final Thoughts

The HTTP 406 “Not Acceptable” error occurs when a server cannot fulfill a client’s requested content format. To fix it, verify the Accept header matches supported formats (JSON, XML, etc.), check server MIME type configurations, and debug framework-specific settings (Django, WordPress). Use tools like cURL, Postman, or browser DevTools to test requests.

Prevent future errors by documenting API requirements and implementing proper content negotiation. With these steps, you can resolve 406 errors efficiently and ensure seamless client-server communication. Still stuck? Consult server logs for detailed insights.

Frequently Asked Questions (FAQs)

What causes a 406 Not Acceptable error?

The HTTP 406 error occurs when a web server cannot generate content that matches the client’s accepted content types. The client browser sends specific content format requirements in its request headers, but the server cannot fulfill these requirements.

How do I fix 406 Not Acceptable in REST API?

Clear your browser cache and cookies first. Check and modify your Accept header to include common content types like “application/json” or “text/plain”. Verify your API endpoint’s content-type matches the Accept header in your request.

Is HTTP 406 a client or server error?

HTTP 406 is a client-side error. The error indicates that the client’s request headers specify content requirements that the server cannot fulfill. The server understands the request but cannot generate the requested content format.

How do I fix 406 Not Acceptable in Chrome?

Reset Chrome’s browser settings to default values. Clear the browser cache and cookies completely. Disable browser extensions temporarily. Check if your browser accepts common content types in its request headers.

How do I fix HTTP 406 in WordPress?

Update your WordPress installation and all plugins. Check your .htaccess file for incorrect content negotiation rules. Verify your server’s content-type configuration. Reset your permalinks structure in WordPress settings.

What is the difference between 406 and 415 status codes?

Error 406 means the server cannot generate content matching the client’s accepted formats. Error 415 indicates the server refuses to accept the request payload format. Both relate to content type issues but from different perspectives.

Priya Mervana

Verified Web Security Experts

Priya Mervana is working at SSLInsights.com as a web security expert with over 10 years of experience writing about encryption, SSL certificates, and online privacy. She aims to make complex security topics easily understandable for everyday internet users.