You may get an error on browser like below,

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

You need to check in your apache error log /apache-path/logs/error.log
# tail  -f  /usr/local/apache/logs/error.log

[Sun Jun 08 10:47:35.739290 2014] [:error] [pid 1010635:tid 140727447172864] [client] ModSecurity: Access denied with code 406 (phase 2). Pattern match "\\\\%(?![0-9a-fA-F]{2}|u[0-9a-fA-F]{4})" .......

When a browser sends a request to the server, The Accept header should be match with mod_security rule, If it does not match sends to  406 error Not Acceptable.

This error can be generated by the mod_security module, it’s  a type of firewall security and  configured in apache server,

If you require to disable mod security to simply apply the rule “SecRuleEngine Off” in your Virtual Host,
# /usr/local/apache/conf/httpd.conf

    ServerAlias www.
    DocumentRoot /home/domain/public_html
    UserDir enabled domain
    <IfModule mod_suphp.c>
        suPHP_UserGroup domain domain
<IfModule mod_security2.c>
SecRuleEngine Off


Finally restart apache server:
/etc/init.d/httpd restart

I hope,  you will never face this issue again.