I'm getting the same message (warning?) with code version 2.4.4 (de943e150d36f815a02d4996e532a5e4e7510bc8) and PHP 7.2.3 (XAMPP 2018-03-14) with debugging on.
This message seems to be related to trying to change the ini setting after the session has started, which was being silently ignored in earlier versions of PHP but is now being reported. Refer https://stackoverflow.com/questions/48209844/ini-set-fails-to-set-session-variables-php-7-2-0-and-higher
I propose that the ini_set be moved before the new SessionManager() [as follows]
-------------------------------------------------------
includes/session.inc | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/includes/session.inc b/includes/session.inc
index 3f8c525d..779dc4e6 100644
--- a/includes/session.inc
+++ b/includes/session.inc
@@ -394,6 +394,9 @@ function login_timeout()
if (file_exists($path_to_root.'/'.$ext['path'].'/hooks.php'))
include_once($path_to_root.'/'.$ext['path'].'/hooks.php');
}
+
+ini_set('session.gc_maxlifetime', 36000); // 10hrs
+
$Session_manager = new SessionManager();
$Session_manager->sessionStart('FA'.md5(dirname(__FILE__)));
@@ -429,7 +432,7 @@ function login_timeout()
*/
// ini_set('session.save_path', VARLIB_PATH.'/');
-ini_set('session.gc_maxlifetime', 36000); // 10hrs
+// ini_set('session.gc_maxlifetime', 36000); // 10hrs
hook_session_start(@$_POST["company_login_name"]);
-------------------------------------------------------
Thanks.