Steps to reproduce the issue

When using PHP 8.4

On all my sites (42) i upgraded to PHP8.4 with joomla 6.0.2.
After that we got alot of error (500 server error) and the only way to solve this problem was to disable opcache in the php.ini

Is this a bug ?

[08/Jan/2026:10:18:36 +0100] "GET / HTTP/2.0" 500 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36 Edg/143.0.0.0" 2026/01/08 10:18:36 [error] 12136#12136: *12 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught TypeError: iterator_count(): Argument #1 ($iterator) must be of type Traversable|array, Closure given in /var/www/website/libraries/vendor/paragonie/sodium_compat/autoload-php7.php:9 Stack trace: #0 /var/www/website/libraries/vendor/paragonie/sodium_compat/autoload-php7.php(9): iterator_count() #1 /var/www/website/libraries/vendor/paragonie/sodium_compat/autoload.php(41): require_once('...') #2 /var/www/website/libraries/vendor/composer/autoload_real.php(41): require('...') #3 /var/www/website/libraries/vendor/composer/autoload_real.php(45): {closure:ComposerAutoloaderInitf577684c10af21b55e694ebddac803ca::getLoader():37}() #4 /var/www/website/libraries/vendor/autoload.php(25): ComposerAutoloaderInitf577684c10af21b55e694ebddac803ca::getLoader() #5 /var/www/website/libraries/bootstrap.php(34): require('...') #6 /var/www/website/includes/framework.php(17): require_once('...') #7 /var/www/website/includes/app.php(29): require_" while reading response header from upstream, client: 2a02:22a0:eee3:cb00:469c:aa9c:365c:89f, server: oa-judo.nl, request: "GET / HTTP/2.0", upstream: "fastcgi://unix:/var/run/php/php8.4-fpm.sock:", host: "oa-judo.nl"

The way we fixed it in the php.ini:

[opcache]
; Determines if Zend OPCache is enabled
opcache.enable=0

; Determines if Zend OPCache is enabled for the CLI version of PHP
opcache.enable_cli=0