blank pages when upgrading to 2.10 zencart - unusual time stamp error logs

[HeathenMagic]

php 8.2 , tried php 8.3 also. Zencart 2.10

I wonder if someone might know what is causing these logs at all please? I am getting blank page on admin and store, it seems to be just the following error log. I had similar error when upgrading the dev site from 2.01, and did the 2.10 update carefully. Either I have done something really stupid or its a server related issue. I do recall having to do a fix for time / date at a previous upgrade juncture as I found a few others at that time having the same error. But I tried searching for some of these error warning snippets, but no results. Thanks in advance.

[24-Feb-2025 23:12:21 Europe/London] Request URI: /************//index.php?cmd=alert_page, IP address: 81.100.177.88, Language id 1
#0 /home/t**public_html/************/includes/init_includes/init_errors.php(160): zen_debug_error_handler()
#1 /home/t**/public_html/************/includes/autoload_func.php(40): require_once('/home/t**/...')
#2 /home/t**/public_html/************/includes/application_top.php(40): require('/home/t**r/...')
#3 /home/t**/public_html/************/alert_page.php(7): require('/home/th**/...')
#4 /home/**r/public_html/************/index.php(16): require('/home/t**/...')
--> PHP Warning: Undefined array key "coupon_expire_date" in /home/t**/public_html/test_store************/includes/init_includes/init_errors.php on line 160.

[24-Feb-2025 23:12:21 Europe/London] Request URI: /************//index.php?cmd=alert_page, IP address: 81.100.177.88, Language id 1
#0 /home/t**/public_html/************//includes/functions/functions_dates.php(325): zen_debug_error_handler()
#1 /home**/public_html/************/includes/init_includes/init_errors.php(160): zen_date_diff()
#2 /home/**r/public_html/************/includes/autoload_func.php(40): require_once('/home/**/...')
#3 /home/t**r/public_html/************/************/includes/application_top.php(40): require('/home/**/...')
#4 /home**/public_html//************/alert_page.php(7): require('/home/**/...')
#5 /home/t**r/public_html//l************/index.php(16): require('/home/**/...')
--> PHP Warning: Undefined array key 1 in /home/**/public_html/************/includes/functions/functions_dates.php on line 325.

[24-Feb-2025 23:12:21 Europe/London] Request URI: /**/index.php?cmd=alert_page, IP address: 81.100.177.88, Language id 1
#0 /home/**public_html/************//includes/functions/functions_dates.php(326): zen_debug_error_handler()
#1 /home/**/public_html/************//includes/init_includes/init_errors.php(160): zen_date_diff()
#2 /home/**/public_html************//includes/autoload_func.php(40): require_once('/home/**/...')
#3 /home/**r/public_html/************//includes/application_top.php(40): require('/home/**/...')
#4 /home/t**/public_html/************//alert_page.php(7): require('/home/**/...')
#5 /home/t**/public_html/************//index.php(16): require('/home/**/...')
--> PHP Warning: Undefined array key 2 in /home/**r/public_html/************//includes/functions/functions_dates.php on line 326.

[24-Feb-2025 23:12:21 Europe/London] PHP Fatal error:  Uncaught TypeError: mktime(): Argument #6 ($year) must be of type ?int, string given in /home/**/public_html/************//includes/functions/functions_dates.php:329
Stack trace:
#0 /home/t**/public_html/************//includes/functions/functions_dates.php(329): mktime()
#1 /home/t**/public_html/************//includes/init_includes/init_errors.php(160): zen_date_diff()
#2 /home/t**r/public_html/************//includes/autoload_func.php(40): require_once('/home/**/...')
#3 /home/t**/public_html/************//includes/application_top.php(40): require('/home/**/...')
#4 /home/**/public_html/************//alert_page.php(7): require('/home/**/...')
#5 /home/t**/public_html/************//index.php(16): require('/home/**/...')
#6 {main}
  thrown in /home/**/public_html/************//includes/functions/functions_dates.php on line 329

[24-Feb-2025 23:12:21 Europe/London] Request URI: ************/index.php?cmd=alert_page, IP address: 81.100.177.88
--> PHP Fatal error: Uncaught TypeError: mktime(): Argument #6 ($year) must be of type ?int, string given in /home/**/public_html/test_store/includes/functions/functions_dates.php:329
Stack trace:
#0 /home/**r/public_html/************/functions/functions_dates.php(329): mktime()
#1 /home/**/public_html/************/includes/init_includes/init_errors.php(160): zen_date_diff()
#2 /home/**/public_html/************/includes/autoload_func.php(40): require_once('/home/**/...')
#3 /home/**/public_html/************/includes/application_top.php(40): require('/home/**/...')
#4 /home**/public_html/************/alert_page.php(7): require('/home/**/...')
#5 /home/**r/public_html/************/index.php(16): require('/home/**/...')
#6 {main}
  thrown in /home/**/public_html/************//includes/functions/functions_dates.php on line 329.

[24-Feb-2025 23:12:21 Europe/London] Request URI: /************//index.php?cmd=alert_page, IP address: 81.100.177.88
--> PHP Fatal error: Uncaught TypeError: mktime(): Argument #6 ($year) must be of type ?int, string given in /home/************//includes/functions/functions_dates.php:329
Stack trace:
#0 /************/public_html/************/includes/functions/functions_dates.php(329): mktime()
#1 /************/public_html/************//includes/init_includes/init_errors.php(160): zen_date_diff()
#2 /************/public_html/************//includes/autoload_func.php(40): require_once('/home/**/...')
#3 /************/public_html/************//includes/application_top.php(40): require('/home/**/...')
#4 /************/public_html/************//alert_page.php(7): require('/home/**/...')
#5 /************/public_html/************//index.php(16): require('/home/**/...')
#6 {main}
  thrown in /************/public_html/************//includes/functions/functions_dates.php on line 329.