In WordPress, when entering posts, you might see the server error
“Error 406, Not Acceptable. An appropriate representation of the requested resource /wp-admin/post.php could not be found on this server”
I got this error only for a post some with code. On creating a new post without any code, it was saved without any trouble.
This is technically not a WP error, but caused by a security filter installed on the part of your web server. ModSecurity, an open source web app firewall, likely caused this error.
Fix 406 not acceptable error
Open the .htaccess file in your blog root (ie. the folder which contains wp-includes) and add the line
This turns off the security filter. Note that this reduces the security of your server, as ModSecurity is put in place for a reason.
Save it and try to publish the post that gave you the error – it should be fixed now. If this fix did not work for you, you may have to contact your web host.