Fatal error (in cleanup?) on upgrade to 3.11.8

Hi,
I've upgraded our beta environment (php v8.0.22) from 3.10.5 to 3.11.8, and after running upgrade.php, there was a fatal error near the end. I presume this is part of the clean-up, so not as fatal as the error message suggests? If so, do I need to run anything, or will this be resolved the next time I upgrade?

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Starting from 28 Updates are being applied to xerte_beta
Current database version - 28

Updating database:

- from version: 28

(If the update doesn't work, run setup.php?debug=1 to see the detailed error messages and SQL queries.)
Updating to version 29 1
DEBUG Query: CREATE TABLE IF NOT EXISTS `educationlevel` ( `educationlevel_id` int(11) NOT NULL AUTO_INCREMENT, `educationlevel_name` char(255) DEFAULT NULL, PRIMARY KEY (`educationlevel_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci, output 1

Creating educationlevel table - ok ? trueFilling default educationlevel into educationlevel table - ok ? true

Updating to version 30
Skip step 30 - Done by 33 - ok ? true
Updating to version 31
Creating Social Icon settings fields - ok ? true
Updating to version 32
Creating folder_parent field in folderrights - ok ? true
Updating to version 33
Creating tsugi_manage_key_id field in templatedetails - ok ? true
Upgrade complete

Cleanup up files that are really in the way
File themes/Nottingham/blackround/responsivetext.css not found (already deleted )
File themes/Nottingham/btnTopPurple/responsivetext.css not found (already deleted )
File themes/Nottingham/darkgrey/responsivetext.css not found (already deleted )
File themes/Nottingham/flatblue/responsivetext.css not found (already deleted )
File themes/Nottingham/flatred/responsivetext.css not found (already deleted )
File themes/Nottingham/flatwhite/responsivetext.css not found (already deleted )
File themes/Nottingham/orangepurple/responsivetext.css not found (already deleted )
File themes/Nottingham/sketch/responsivetext.css not found (already deleted )
File modules/xerte/parent_templates/Nottingham/common_html5/mediaelement/DO NOT CHANGE THESE FILES. USE -src- FOLDER.txt not found (already deleted )
Removing USER-FILES/*/.htaccess

Fatal error: Uncaught Error: Call to undefined function system() in /usr/local/projects/xerte/www/html/upgrade.php:226 Stack trace: #0 /usr/local/projects/xerte/www/html/upgrade.php(139): _do_cleanup() #1 {main} thrown in /usr/local/projects/xerte/www/html/upgrade.php on line 226

Do you happen to have system() disabled in php.ini?

It is not really an issue. You could enable it, run upgrade and enable it again.

Next time you run upgrade, the same will happen again.

Thanks for the reassurance Tom.

I've had a look in php.ini but there was no mention of system(), so I presume it's enabled.