fwrite(): Argument #1 ($stream) must be of type resource, false given

/data01/virt82355/domeenid/www.sportos.ee/www-sportos-eu/common/functions.inc.php1742fwrite
  /data01/virt82355/domeenid/www.sportos.ee/www-sportos-eu/code/kernel/user/User.class.php2598log2file
    /data01/virt82355/domeenid/www.sportos.ee/www-sportos-eu/code/kernel/user/User.class.php25releaseLockedAccountsUser
      /data01/virt82355/domeenid/www.sportos.ee/www-sportos-eu/code/kernel/Application.class.php275__constructUser
        /data01/virt82355/domeenid/www.sportos.ee/www-sportos-eu/index.php225__constructApplication