php session Cannot send session cookie -

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• how fix “headers sent” error in php 11 answers

i trying solve error related session in php. please me. thankyou!

warning: session_start(): cannot send session cookie - headers sent (output started @ c:\xampp\htdocs\myfolder\login.php:117) in c:\xampp\htdocs\myfolder\login.php on line 155

warning: session_start(): cannot send session cache limiter - headers sent (output started @ c:\xampp\htdocs\myfolder\login.php:117) in c:\xampp\htdocs\myfolder\login.php on line 155

here php code:

$adm_user=$_post['username']; $adm_pass=$_post['password']; if($adm_user=="" || $adm_pass=="") {     echo'fields cannot empty'; } else {     $adm_login_sql="select admin_login.username, admin_login.password                     admin_login                     username='$adm_user' , password='$adm_pass'";      $adm_login_query=mysql_query($adm_login_sql);      if (!$adm_login_query)         {         echo "error: no records found" . mysql_error();         }     else         {             echo "query successful<br>";              $adm_login_row=mysql_fetch_array($adm_login_query);              $check_uname=$adm_login_row[0];             $check_pass=$adm_login_row[1];                   if($check_uname==$adm_user && $check_pass==$adm_pass)                 {                     session_start();                     $_session['name']=$adm_user;                      header('location:admin.php');                    }                 else                 {                     echo 'password missmatch!!!';                 }          } } 

"headers sent" means php script already sent http headers, , such can't make modifications them now.

check don't send content before calling session_start(). better yet, make session_start() first thing in php file (so put @ absolute beginning, before html etc).