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How to Fix “406 Not Acceptable” Error?

The 406 Not Acceptable error is a HTTP response code signaling a more complicated issue related to content negotiation between the client side and server side. Server and client-side errors occur occasionally, and we commonly call them HTTP status codes or HTTPS status code errors. The “406 error” or “406 Not Acceptable” error is one of such HTTP response codes..

You may face 406 error while visiting a site. It may irritate every internet user, it can be terrifying for website owners. Besides looking somewhat unprofessional and confusing, any HTTP status code, including the 406 error, can impact sales and number of users.

In this comprehensive tutorial we will explain the basics of the “406 Not Acceptable” error, its root causes, and how to fix 406 error, and best practices to avoid 406 status code in the future. So let’s Start.

What is “406 Not Acceptable” Error?

The 406 status code error is about the content negotiation. Content negotiation is a process where the client and server exchange information about the types of content the client can process and what the server can provide. This exchange is facilitated through HTTP headers, with the ‘Accept’ headers playing an important role. These headers allow the client to specify formats, languages, encodings, and character sets it can handle.

It is necessary to be familiar with HTTP request response cycles in order to understand 406 Not Acceptable.The client is willing to accept a request sent by the client to the server using Accept-headers. These headers, which describe the client’s preferences for media types, character sets, content encodings, languages, and ranges of bytes it can process, can include Accept, Accept-Charset, Accept-Encoding, Accept-Language, and Accept-Ranges.

The 406 error occurs when the server’s response does not align with any of those media types listed. The server essentially responds that it is incapable of delivering content in a format acceptable to the client based on the provided criteria.

What are HTTP Status Codes/Response Code?

Before we take steps to fix “406 Not Acceptable” error, it will be helpful to have a basic knowledge of HTTP status codes. These codes are part of the HTTP protocol, which is the foundation of any data exchange on the web.

HTTP status codes are three digit number codes that indicate the result of a client’s request to a server. They are categorized into five groups:

  • 1XX : It means the request was received, and the process is continuing.
  • 2XX : It indicates that the request was successfully received and accepted.
  • 3XX : It shows further action needs to be taken to complete the request.
  • 4XX : It indicates that the request contains bad syntax or cannot be fulfilled.
  • 5XX : The server failed to fulfill a valid request.

The “406 Not Acceptable” error falls into the 4XX category, indicating client-side issues. However, it often requires server-side adjustments to resolve.

Root Causes of 406 Not Acceptable Error

Before taking the right step to fix the error we need to understand root causes of 406 error. There are several causes of occurring “406 Not Acceptable” Error.

1. Accept-ranges

    Some servers have security measures to allow a specific limited file size range in the response. If the response attempts to cross the range, you’ll see the 406 error.Hence Security settings and server configurations that limit the size of content can trigger a 406 error if the response exceeds those limits..

    2. Accept-encoding

      Here’s an area of the header to compress files, so they can move quickly from the server to the browser. Some compression methods and formats aren’t accepted, rendering a 406 error code. A 406 error might occur if the server attempts to use an unsupported encoding format.

      3. Accept-charset and accept-language

        There are so many characters, languages, and symbols in the world that it’s challenging to cover them all. New character tables occasionally get released to keep up with language and character additions.These relate to the encoding of characters and the language of the content. A mismatch in character sets or language preferences can lead to a 406 error.This is usually a different name for Accept-charset that references its focus on international languages

        4. MIME Type Violation

          Sometimes, the browser requests a special MIME type from the server. MIME types are content like JPEG images, specific video formats, or simple text. If the server can’t provide a requested MIME type, you’ll face a 406 error. Means a 406 error can also occur when the server is unable to provide content in a MIME type that the client accepts. This is important  to deliver the right content type, such as images or videos, in a format the client can handle.

          Fixing “406 Not Acceptable” Error

          Fixing this error includes a series of troubleshooting steps focused at identifying and rectifying the mismatches between the client and the server. 

          Server-Side Solutions

          If the issue is server-side, here are some steps you can take to resolve it.

          1. Check Server Configuration

            Review and check your server configuration files to ensure they are set up correctly to handle the requested content types.

            2. Adjust Server Settings

              You might need to adjust settings related to content negotiation and MIME types to ensure compatibility with client requests.

              3. Update Server Software

                Update your server software. Ensure that your server software version is up to date, as older versions might not support the latest content negotiation methods.

                Client-Side Solutions

                When the issue is on the client side, the following steps can help.

                1. Check Requested URL

                  A mistyped, outdated, or improper URL can request resources that the server cannot correctly interpret or does not have, resulting in a 406 error. This step is critical because it addresses the potential human error element in the equation, ensuring that the request itself is valid and correctly directed.

                  Correcting the URL ensures that the request is sent to the right location of the resource and server can understand and process. It can eliminate the possibility of a 406 error arising from a miscommunication between the client and server due to an incorrect resource identifier.

                  2. Restart Devices and Network Connection

                    Restarting your devices and internet can be considered as an effective way to resolve a broad spectrum of network-related issues, including a 406 Not Acceptable error. This step can be particularly effective if the error is a result of temporary networking glitches, DNS issues, or stale configurations on your device or network equipment.

                    To restart your internet connection unplug your modem and router from the power source, wait for at least 30 seconds, and then plug them again and wait for the devices to fully restart and connect to the internet.

                    Once your modem and router are back online, reconnect your device to the network and try accessing the URL again.

                    3. Clear Browser Cache

                      Sometimes, clearing the browser cache can resolve 406 error. Old cache data might be conflicting with new server configurations.

                      4. Disable Browser Extensions

                        Browser extensions can also intefere with content negotiation. Try disabling them to see if the error resolves.

                        5. Update the Browser

                          Ensure your browser is updated to the latest version, as updates often include fixes for compatibility issues.

                          Does 406 Status Code affect Search Engine Optimization (SEO)?

                          A 406 Not Acceptable status code can potentially affect SEO. If it is preventing search engines from properly indexing the affected resource. it could negatively impact ranking of the affected page or site in search engine results pages (SERPs). This can ultimately result in decreased traffic and visibility for the affected site.

                          Best Practices and Tips for Preventing  406 Not Acceptable Error

                          To ensure that this error doesn’t happen in future on your website, here are some best practices and tips for avoiding “406 Not Acceptable”:

                          • Clean your database and keep arranged your site files. Doing this regularly is good, and it’s better to use a tool that does it for you automatically.
                          • Only use plugins, themes, and add-ons from trusted sources and that you really need. Try not to add too many.
                          • Don’t change the main WordPress files unless you really have to.
                          • Set up your website to back up automatically if something goes wrong, you need not to worry because you can go back to an earlier version of your website and start over.
                          • Also do manual backup before you update WordPress or any plugins, even if you have automatic backups set up. This is just to be extra safe.
                          • Use our comprehensive WordPress Management Services for premier quality all type managed WordPress solutions, ensuring your website runs smoothly, securely, and efficiently without any errors and you can focus on your core business.

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                          In conclusion, fixing 406 Not Acceptable involves a comprehensive approach that addresses potential issues from incorrect URLs to issues related to content management systems, plugins, themes, databases, and server configurations. 

                          Each step of fixing error targets a specific area where mismatches between the client’s and server may occur. By using these troubleshooting steps, you can identify and resolve the underlying cause of the error, ensuring that your website can once again deliver content successfully to its users.

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