Server and client-side errors happen occasionally, and we commonly refer to them every bit HTTP responses or status codes. The "406 error" or "406 Not Acceptable" mistake is one such HTTP response.

You may see the 406 error while visiting a site. Or worse, on your website. While It may irritate the average internet user, it can be borderline terrifying for a website or awarding owner. Likewise looking somewhat unprofessional and confusing, any HTTP response code, including the 406 error, can lose sales and users.

This article will explain the basics of the "406 Non Acceptable" error, its causes, how to prepare it, and steps to avoid it in the futurity.

Check Out Our Guide to Fixing a 406 Mistake and Find the Source of the Problem

What Is 406 Error?

The good news is that the HTTP error "406 Non Adequate" message is non nearly as mutual as the 404 server error (which usually indicates a non-real webpage), or even 301 or 500 HTTP errors. Therefore, yous definitely shouldn't encounter this ane as much.

Although it's rare, it's nevertheless possible that the 406 error may come up into play every bit a problem for your website. It unremarkably looks like this:

A screenshot of 406 error in a browser.
One example of a "406 Not Adequate" bulletin.

The message typically reads:

Not Acceptable

An appropriate representation of the requested resource could not be institute on this server.

It and so sometimes identifies the "requested resource" where the trouble lies, with other messages or server data mentioned at the end:

406 not acceptable message with the blocked resource
Some 406 errors show the rejected resource.

The appearance and text within the 406 error message depending on the website, host, and browser used to access the website. The 406 fault may reveal where the errors stem from. Other times you may observe that it'southward a simple "406 Not Adequate" error without any information helping you solve the problem.

Now, let'due south pretend browsers spoke in apparently English and not these cryptic letters. In that instance, the browser would be maxim something like this:

Hello, I'm a browser. I tried to show this webpage, but one of the two bug occurred:

  1. The website's server sent me the incorrect file format, and so I tin can't accept it.
  2. The website's server violates some settings or security requirements.

Therefore, please resolve the violation or take the server employ i of the file formats I accept. In case you're wondering, here are the file formats I know how to read.

If only browsers were that friendly!

Essentially, at that place'southward a miscommunication betwixt the server and the browser or machine used to present the web awarding. The browser either can't read what's coming in or verify the information because it didn't run across some requirements.

Now nosotros have to answer some questions to effigy out the cause of that miscommunication.

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What Causes the 406 Error?

Every time you open a web folio, your browser (like Safari, Firefox, Dauntless, Chrome, or Cyberspace Explorer) sends a asking to the folio's server to obtain site content and database files. The browser acts every bit the messenger between you and the server — information technology tells the server what the user wants to come across, and hopefully, the correct information comes dorsum.

During that outset request, the browser tells the server all almost the file formats information technology can accept. It'southward called an Accept- header request, which prompts the server to deliver the files in the proper formats to produce the entire website or web application, starting with the header.

Sometimes the server sends a reply that'south not in the suitable format or violates a rule set along by the browser or client machine. In this situation, a 406 error appears in the browser window, indicating the server isn't delivering the appropriate information.

Here are some examples of "bad formats" and "rule violations" that can come up with the header requests:

  • Accept-ranges: Some servers take security measures set in place or only allow a specific file size range in the response. If the response attempts to send too many bytes outside the allowable range, you'll meet the 406 mistake.
  • Accept-encoding: Here's an surface area of the header meant to compress files, so they move quickly from the server to the browser. Some compression methods and formats aren't accustomed, rendering a 406 error code.
  • Accept-charset: Refers to a character gear up or how site file tables take code (like CSS and HTML) and plough information technology into understandable characters. There are and then many characters, languages, and symbols in the globe that it'southward challenging to cover them all. The standard table is called ISO-8859, but at that place are other complementary tables as well. New graphic symbol tables occasionally get released to go on upward with linguistic communication and character additions.
  • Accept-linguistic communication: This is unremarkably a different proper name for Accept-charset that references its focus on international languages.
  • MIME type violation: Sometimes, the browser requests a specific MIME type from the server. MIME types are content elements similar JPEG images, specific video formats, or simple text. If the server tin't provide a requested MIME type, like JPEG images, you'll see a 406 error.

The primary way to address and ready a 406 error is by checking the source code for issues in the Accept-, Asking-, and Response- headers.

The easiest way to review Accept- and Response- headers is to open a webpage in your browser, correct-click, and select Inspect.

Go to Network > Headers to reveal all requests from this webpage.

network and header buttons
Right-click and choose Inspect in the browser, then go to the Network and Headers tabs.

You tin typically select any request from the long list to see the Request- and Response- headers for that particular request.

finding the response headers for the 406 error
Click on whatsoever request in the list to meet things like Response- and Asking- headers.

Or, you tin can contact your spider web developer to take a look into the source code. However, checking the source code is much easier when y'all have tools for debugging and cleaning your database, which nosotros'll hash out later in this article.

As mentioned before, a "406 Non Adequate" error tells united states that the client has sent a valid request to the server, only the request included a unique requirement for the server to follow. That special requirement in the initial request was in the form of an HTTP Accept- header.

That leaves us with a few potential causes:

  1. The server didn't provide the requested MIME type or proper formats, like a JPEG or mp4 video.
  2. The server didn't return with the correct linguistic communication (Accept-linguistic communication). For instance, it may have sent back a response in German when the browser asked for French.
  3. The server used the wrong compression method or format in response to the Accept-encoding request.
  4. The server sent back likewise many bytes that didn't align with the Accept-ranges request.
  5. The server failed to provide understandable characters, which would result in a problem with the Accept-charset request from the browser.

In that location are other reasons you may see the 406 error, just they're non nigh equally mutual. The in a higher place list is from the well-nigh mutual reasons to the to the lowest degree common. The offset two come up into play far more often than the others, and so in that location'south a good take a chance yous should unremarkably focus on troubleshooting the potential for a MIME blazon violation or an Take-language problem.

Overall, website owners should know almost these format bug and violations, seeing how something within your site files may cause bug. Such situations often occur because of man error, like accidentally typing in the wrong lawmaking, deleting necessary code, or misconfiguring the server. The 406 fault also appears when specific security settings or rules cake content transmission from the server.

How to Fix the 406 Error

It's prudent to run a website or application backup earlier completing any steps to resolve a 406 error. At that place'southward ever the potential for causing farther problems by going into your site'south source code, so yous'll want to have a database and site file backup to restore if necessary.

Make sure you consummate a full backup with everything from the database to the application and the media elements to the site files. If you're a Kinsta user, you lot can do this with the MyKinsta backup feature, which logs your entire website in a separate file and has a Restore button for later use:

backups to help with 406 error
Run Daily, Hourly, or Manual backups in the MyKinsta dashboard.

Now that nosotros have a deeper understanding of why the 406 error occurs, it'southward time to talk about the best methods to troubleshoot the error and prevent it from happening again.

These tactics include client-side causes (where a user makes an error or the automobile isn't working correctly), server-side causes, and platform-based causes like faulty plugins.

Brand Sure the URL Is Right

Our first piece of advice may audio elementary, but it'southward the quickest troubleshooting option, and it puts a focus on issues with the client-side of things (i.eastward., your estimator).

A 404 fault is far more likely than a 406 fault in this state of affairs, but you may end up seeing a "406 Not Adequate" error if the website URL is valid. Yet, there's something odd about the way your browser translates the request. For instance, adding "JSON" or "PHP" to the end of URLs could be misinterpreted as a request for those particular formats, fifty-fifty though the customer doesn't need them.

To resolve the outcome, double-check the previously used URL that produced the error. Endeavour typing information technology in again or opting for a unlike subdomain on the website to meet if it's only one page that isn't rendering.

A 406 message is technically considered a customer-side error code (even though it's oft a platform or server issue), and then this is the commencement class of action to determine if something's wrong on the client side.

Reset Your Devices and Networks

Another client-side problem occasionally involves those same Accept- headers sent from the user'south reckoner to a platform that can't satisfy the request. Many of these platforms include gaming- or media-oriented systems like Hulu or music marketplaces similar Spotify.

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In simpler terms, you may log into a platform like Hulu, endeavour to lookout man your favorite TV testify, and receive a 406 fault bulletin. In this example, the problem is almost always on the client-side. It's usually your calculator, network, or another device y'all've used to launch the platform.

Although it can happen with whatsoever platform, some platforms that commonly report 406 errors include:

  • Hulu
  • Google Play
  • Square Enix Games
  • Netflix
  • Xbox
  • Windows (ordinarily for gaming)

This list is far from complete, merely information technology gives you an idea of where the 406 error may occur.

Media and gaming platforms are complicated with many restrictions, and those restrictions depend on your location or network configuration. At that place's a chance yous might encounter an error like this due to all the moving pieces.

Although we can't aid you troubleshoot every specific platform, consider walking through the following recommendations and checking to see if the mistake resolves:

  • Become online to cheque the status of your platform'due south server. It may simply exist a trouble with the company's server.
  • Restart your calculator, gaming system, streaming device, or other machines.
  • Disconnect all devices from their cables, wait a few minutes before reconnecting them all, and check to meet if the error is gone.
  • Cheque if the app is running the most current version. Also, see if whatever of your machines accept firmware updates available.
  • Reset your home or part network (the WiFi or internet connection through your router).
  • Consider switching from a wireless network to a wired network connection if you're still having trouble.
  • Although this isn't always a possibility, consider duplicating the fault with a completely different machine. Make sure that the device is on the same network. If you tin't replicate the fault, look into your network and the original machine.

If all else fails, become to your search engine and type in the name of your platform forth with "+ 406 fault code" for platform-specific troubleshooting communication. That oftentimes reveals forums and support documentation to guide you through the process.

Rollback Your Contempo CMS Changes

Next, it's time to explore the organization used for your websites or applications. You lot may detect that your content direction system, such as WordPress, is the straight cause of a "406 Not Acceptable" error due to a complication with something inside your site files.

Whether using WordPress or any other content management arrangement, look into when your last update occurred. WordPress has a sturdy default infrastructure meant to avoid these types of errors, no thing what.

Withal, specific plugins, themes, or manually adjusted coding could produce situations where the site files violate client or server requests. A unproblematic upgrade to your CMS'southward latest version can solve the problem right abroad.

To figure out if it's your CMS, outset past rolling back whatever recent upgrades that occurred to the core files. As you may already know, WordPress sends out updates to its system regularly. Most of these updates happen automatically, only older versions withal require you to click a push.

Furthermore, WordPress and other CMSs utilize several moving parts similar plugins, themes, and extensions. Those likewise go updated regularly, so yous might demand to roll dorsum some of them.

For all systems outside of WordPress, search for "platform name + how to downgrade."

If yous utilize WordPress, you tin can easily downgrade your WordPress website, effectively rolling it back to one of the previous versions:

the wordpress version in the dashboard
Downgrade to a previous WordPress version.

That guide outlines the following methods for downgrading your WordPress site, most of which only take a few minutes:

  • Manually downgrading your WordPress site.
  • Using a plugin to consummate the WordPress organization downgrade.
  • Restoring a previous backup to bring back an erstwhile version, or at least the content and files from before.
  • Manually downgrading a theme or plugin.
  • Downgrading a plugin or theme with a separate plugin.
  • Switching to an older version of PHP.

Uninstall and Reinstall Plugins, Themes, and Extensions

WordPress plugins and themes add extra code to your site files that interact with the core WordPress files. Reputable plugins typically don't cause any problems, but occasionally a conflict occurs. A plugin, theme, or 3rd-political party extension may exist the reason for the 406 error.

The tried-and-true method for identifying a troublesome plugin or theme is to deactivate your plugins and themes one past ane. After disabling each, bank check to see if the 406 error has vanished. If so, you've plant the problem. If it doesn't go away, reinstall the plugin or theme and continue uninstalling the adjacent one.

deactivate plugins when you see a 406 error
Go to the Plugins tab in WordPress and Deactivate each plugin one by one.

Analyze the Condition of Your Database for Changes and Conflicts

Unfortunately, a removed "problem" plugin could still affect your WordPress database since plugins get total admission to the database to work well. Therefore, yous should still check the status of your database even if information technology appears the removal of a plugin has made the 406 error become away. Otherwise, you may still run the adventure of seeing further issues in the hereafter.

If a plugin or theme wasn't the culprit, y'all should also check your database if it's the primary source of the error. Sometimes a database change, whether accidental or purposeful, becomes the main reason a 406 fault appears.

To scan and prepare your database, consider these solutions:

  1. Install a database scanner and cleaner that removes useless and troublesome tables and assets. Some options include WP Optimize and the Advanced Database Cleaner. Much of this procedure involves deleting one-time or orphaned items like trash posts, revisions, and metadata. It's a solid first stride to cleaning up your database and potentially eliminating that 406 mistake.
  2. Scan the database and look for records and tables potentially inverse by a problematic plugin or ones that look out of identify or unnecessary.
  3. If y'all accept an thought of what'south wrong with your database, go to a search engine and seek out assist from forums and other discussions online. There's a good chance someone else has experienced the same trouble.
optimizing database with plugin
Clean your database with an optimization tool like WP-Optimize. Image Source: WP-Optimize

Analyze Your Server Logs

The previous recommendations focus on client-side and CMS-oriented troubleshooting. Now we'll consider all server-side issues. This tip, and the ones following, are best if you aren't using a CMS or know that the 406 error has no connection to your CMS or client machine.

The kickoff step in troubleshooting the server is checking the logs. It doesn't matter what type of web awarding, CMS, or web design organization you use; they all have server-side logs.

The application logs shop that spider web application'due south entire (or recent) history, with information about each database enquiry, results provided, pages requested, and much more. On the other hand, the server logs comprise information almost the health and status of the server or hardware used to run the spider web application.

For Kinsta users, you lot tin can find mistake and server logs in the MyKinsta dashboard. Bank check all logs that may exist causing the 406 error:

  • The error.log file
  • The kinsta-enshroud-perf.log file
  • The admission.log file
checking logs while troubleshooting the 406 error
To meet the three necessary logs, click on the Sites tab, choose your site, then the Logs button, along with the type of log from the dropdown menu.

Y'all can also check raw access and WordPress error log files with an FTP client. Other options include enabling error logs in wp-config.php and going through the debug mode in the MyKinsta dashboard.

If y'all have problems finding the error logs or don't know how to interpret them, contact the Kinsta client support team for assist.

Debug the Web Application (Like WordPress)

Like well-nigh web applications have server and error logs, they besides typically provide information about debugging the awarding itself. Debugging involves going through the application's lawmaking to find and eliminate minor errors (or bugs).

I of the best ways to run a complete scan of WordPress (and whatever spider web application for that matter) is to debug the database and website files. Luckily, debugging doesn't mean y'all take to read through every line of code and selection out the bugs yourself. Programs are available for this specific purpose, and as we mentioned earlier, Kinsta fifty-fifty has its debugging tool within the MyKinsta dashboard.

Start the debugging process by learning the nuts of debugging WordPress with the Kinsta Debug Mode, WordPress Debug plugins, or a more manual process:

use WordPress debugging for 406 error
Sites > Tools brings you to a page to actuate the WordPress Debugging Mode feature in the Kinsta dashboard.

Preventing the 406 Error in the Futurity

The trouble with the 406 error is that it can pop up in many dissimilar situations. You lot might see the "406 Not Acceptable HTTP" error while browsing through Hulu or Netflix as a regular consumer.

That isn't very pleasant, but nothing a piffling troubleshooting can't gear up. The more concerning occurrence of the 406 error is when it happens on your website or application. For those instances, you'll need to check the server and CMS site files.

If it's your website, yous'll want to prevent the error from ever happening again. Plugins, themes, and human being fault tin always come into play, merely we have a few suggestions to keep your databases and site files make clean into the hereafter:

  • Only install necessary and reputable plugins, themes, and extensions. E'er keep these elements to a minimum.
  • Don't ever change the core WordPress files unless you admittedly must and know what you're doing.
  • Run a database cleaner and site optimizer regularly. We recommend completing this process every calendar month and ideally finding a cleaner plugin that runs automatically in the background.
  • Make a addiction of debugging your server and web awarding. As mentioned, Kinsta offers a Debugging feature in its dashboard. Many other applications accept this type of functionality as well.
  • Fix automated backups of your website or awarding. This way, a lawmaking conflict or error won't cause yous much stress since you can restore a previous version of the website and start from there.
  • Run a manual backup of your site before y'all plan on updating WordPress and any plugins, even if y'all already run automatic backups (meliorate prophylactic than deplorable). It'due south also wise to run backups before editing whatever files or calculation new code to your site.

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Summary

You can gear up the 406 error in several means. Every bit long as you know what you are seeing and where to await for the fix, you should exist able to clear the fault upward.

While this is non one of the more common WordPress errors, information technology is ane you will meet from time to time if your configuration is not correct.

Do yous take any other recommendations for resolving "406 Not Acceptable" errors? Please share them in the comments section below!

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