WordPress is the most popular website platform (32% of the internet on the last count), precisely because it is easy to manage.

But at times, due to certain web server restrictions, an attempt to update the site can result in the “406 Not acceptable error”.

And when website owners do not have a clue on why this error happens, they hit the panic button.

Here at Bobcares, we help website owners to fix their websites as part of our Support Services.

Today, let us discuss the causes for “406 not acceptable error” in WordPress and how we fix them.

What causes “406 not acceptable error” in WordPress ?

We see “406 not acceptable error” largely due to restrictions on the web server.

Most web hosts install a program called “ModSecurity” to protect the web server from malicious actors like spammers, hackers etc.

ModSecurity generally block malicious requests to the web server with a “406 not acceptable error”. But often it blocks legitimate requests as well.

Recently in one of the VPS server that we manage, we saw ModSecurity blocking a genuine request. On trying to Publish a WordPress post, website owner was presented with the error.

Not Acceptable
An appropriate representation of the requested resource /wp-admin/post.php could not be found on this server.

Additionally, a 406 Not Acceptable error was encountered while trying to use an ErrorDocument to handle the request.

Not Acceptable errors need not be limited to server settings always. Browser settings like language, character encoding etc. also can cause 406 not acceptable errors.

How to fix “406 not acceptable” error ?

To fix the error, our Support Engineers analyze the ModSecurity logs and that helps to identify the exact rule that caused the block.

If the request from browser is genuine and ModSecurity wrongly blocked it, we disable this particular rule for the domain.

When selective disabling of rules do not work, the only option left is to Turn OFF ModSecurity completely for the domain.

In cPanel servers, there is an option to do this from the cPanel of the domain.

Conclusion

“406 not acceptable error” in WordPress happens mainly due to restrictions on the Web server. Today we saw the top causes for the error and how our Support Engineers fix them.