v157b PHP Notice: Undefined index: SSL_SESSION_ID

157b, responsive classic, PHP7.3

I turned on extra logging and this turned up, it is a notice so not an error; should I worry about it or ignore it?

[16-Apr-2021 22:14:00 Europe/Zurich] Request URI: /catalog/index.php?main_page=checkout_shipping, IP address: 88.151.150.xxx
#1 require_once(/includes/init_includes/init_sessions.php) called at [/includes/autoload_func.php:37]
#2 require(/includes/autoload_func.php) called at [/includes/application_top.php:219]
#3 require(/includes/application_top.php) called at [/index.php:25]
--> PHP Notice: Undefined index: SSL_SESSION_ID in /includes/init_includes/init_sessions.php on line 132.

It seems you've turned on the Admin->Configuration->Sessions->Check SSL Session ID which is off by default.

I'm guessing that your webserver's configuration (not in your control) isn't currently passing the SSL_SESSION_ID value over to PHP.
I haven't looked into whether that setting is even "common" anymore in modern webserver software.

I guess to mitigate it you have 2 options:
a) turn that configuration setting off
b) or you could explore changing line 131 as follows:

if ( ($request_type == 'SSL') && (SESSION_CHECK_SSL_SESSION_ID == 'True') && (ENABLE_SSL == 'true') && ($session_started == true) [B]&& isset($_SERVER['SSL_SESSION_ID'])[/B]) {

Thanks for your quick reply, I have turned off the Admin->Configuration->Sessions->Check SSL Session ID.