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Resolving 406 Not Acceptable HTTP Status Codes - HTTP Error Code 406

Karthik MSN
~ 8 min read | Published on Mar 28, 2024


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What is a 406 error?

When you encounter a 406 Not Acceptable HTTP status code, it signifies that the server cannot fulfill the request because the client's request header indicates a media type or representation that is not supported for the target resource.

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What are the possible causes for a 406 error?

Several factors can trigger a 406 error. Some common causes include:

1. Unsupported Media Type:

  • The client request specifies an unsupported media type in the 'Accept' header.
  • The server doesn't have the capability to generate a response that satisfies the media type requested by the client.

2. Misconfigured Server:

  • The server is misconfigured and cannot correctly interpret the 'Accept' header.
  • Content negotiation is not properly configured on the server side.

3. Content Negotiation Failure:

  • The server's content negotiation algorithm fails to find a suitable representation for the requested resource.
  • There's a mismatch between the media types supported by the server and those requested by the client.

How to Handle 406 in JavaScript

When handling a 406 error in JavaScript, you can use the fetch API or libraries like Axios. Here's a basic example using the fetch API:

fetch('<>', {
  headers: {
    'Accept': 'application/json' // Specify the desired media type
.then(response => {
  if (!response.ok) {
    throw new Error('Request failed: ' + response.status);
  return response.json();
.then(data => {
  // Process the retrieved data
.catch(error => {
  console.error('Error:', error);

Ensure to include the appropriate media type in the request headers to prevent a 406 error.

Best Practices for Using 406 Status Code

To effectively use the 406 status code, consider the following best practices:

1. Proper Content Negotiation:

  • Implement content negotiation mechanisms on the server to ensure it can respond with an acceptable representation.
  • Support multiple media types to cater to diverse client preferences.

2. Clear Error Messaging:

  • Provide informative error messages to help developers understand why their request was rejected.
  • Include details on supported media types or guidance on how to adjust the request headers.

3. Graceful Error Handling:

  • Handle 406 errors gracefully in client-side code to prevent disruption of user experience.
  • Provide fallback options or alternative resources whenever possible.

How to Test 406 Status Code on Postman

To test a 406 status code using Postman, follow these steps:

  1. Open Postman and create a new request.
  2. Enter the request URL.
  3. Set the request method (e.g., GET, POST).
  4. Navigate to the Headers tab.
  5. Add a header with key 'Accept' and specify an unsupported media type (e.g., 'text/plain').
  6. Send the request and observe the response status code.

How to Test 406 Status Code in DevTools Browser in Chrome

To test a 406 status code using DevTools in Chrome, proceed as follows:

  1. Open Chrome DevTools by pressing F12 or right-clicking on the page and selecting "Inspect."
  2. Go to the Network tab.
  3. Perform the action that triggers the request.
  4. Locate the request in the network activity list.
  5. Check the response headers and body for the status code and details.

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Frequently Asked Questions

Q: What should I do if my server consistently returns a 406 error?

  • A: Check the server configuration, particularly content negotiation settings. Ensure that the server supports the media types requested by clients and properly handles the 'Accept' header.

Q: Can a 406 error occur due to client-side issues?

  • A: Yes, if the client specifies unsupported media types in the request headers or if there's a mismatch between client expectations and server capabilities.

Q: Is it possible to override the default 406 error response?

  • A: Yes, servers can be configured to customize error responses, including the content and HTTP status code. However, it's crucial to adhere to HTTP standards and provide meaningful error information.

Q: How can I troubleshoot a 406 error in a RESTful API?

  • A: Review the API documentation to understand the supported media types and ensure that your request aligns with those specifications. Use tools like Postman or browser DevTools to inspect request and response headers for discrepancies.

Q: Are there security implications associated with 406 errors?

  • A: While 406 errors themselves do not pose security risks, they can indirectly impact security if they expose information about server configurations or potential vulnerabilities. Ensure error messages are appropriately sanitized to prevent information leakage.


In conclusion, understanding and effectively resolving 406 Not Acceptable HTTP status codes are essential for maintaining smooth communication between clients and servers. By following best practices in content negotiation, error handling, and testing, developers can mitigate issues related to 406 errors and ensure a better user experience. For comprehensive error monitoring and management, consider leveraging tools like Zipy, which offer session replay capabilities and insights into error occurrences. Visit Zipy for more information.

Read more resources on 4xx error status codes

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