I get error 413 every time i try to post data with php script using curl. I can "get" web pages,but when i use "post" the script dies with

does not allow request data with POST requests, or the amount of data provided
 in the request exceeds the capacity limit.

I have a py script,which works. Here is an example code that doesn't work:

 $q=curl_init(POSTURL);

 curl_setopt($q,CURLOPT_POST,true);
 curl_setopt($q,CURLOPT_RETURNTRANSFER,true);


 $post=array("q"=>2);
   $ss=curl_setopt($q,CURLOPT_URL,"http://localhost");
        curl_setopt($q,CURL_POSTFIELDS,$post);
 $f=curl_exec($q);
 curl_close($q);
        echo $f." is error"; 

Sorun apache ile eğer benim komut dosyası veya başka bir şey ile, bilmiyorum.