PHP doesn't create session -

after check, that's problem actually:

warning: unknown: write failed: no space left on device (28) in unknown on line 0  warning: unknown: failed write session data (files). please verify current   setting of session.save_path correct (/mnt/ramdisk) in unknown on line 0 

add session_start() in beginning of code this, , see if helps.

session_start(); $file = fopen($path, "r");         if($file)          {             if(isset($_post['login']))             {                 while(($line = fgets($file)) !== false)                  {                     $user_data=explode(";", $line);                      if($_post['login']==trim($user_data[0]))                     {                         if(md5($_post['pass'])==trim($user_data[1]))                         {                             $_session['logged']=htmlspecialchars($_post['login']);                             header('location:vms.php');                             break;                         }                     }                 }                 echo "                         <script>                             alert('invalid login or password');                         </script>                     ";             }         }