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 192.168.0.2] 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

<VirtualHost 192.168.0.1:80>
    ServerName domain.in
    ServerAlias www. domain.in
    DocumentRoot /home/domain/public_html
    ServerAdmin webmaster@domain.in
    UserDir enabled domain
    <IfModule mod_suphp.c>
        suPHP_UserGroup domain domain
    </IfModule>
...
<IfModule mod_security2.c>
SecRuleEngine Off
</IfModule>
 ....

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

I hope,  you will never face this issue again.