Php versions – Laravel 10 to 11: Call to undefined method ReflectionFunction::isAnonymous()

I recently upgraded my Laravel application from version 10 to 11, and I’ve encountered a runtime error that I’m unable to resolve. The error message is as follows:

Call to undefined method ReflectionFunction::isAnonymous() at 
/var/www/myproject/vendor/laravel/framework/src/Illuminate/Container/Container.php:680

This issue appears immediately after upgrading to Laravel 11, and disappears when I revert back to Laravel 10. Here are some key details about my environment and the upgrade process:

PHP Version: 8.3.1

Symfony components upgraded from v6.4.x to v7.0.x 
nunomaduro/termwind from v1.15.1 to v2.0.1 
symfony/clock from not present to v7.0.5 
carbonphp/carbon-doctrine-types from 2.1.0 to 3.2.0 
nesbot/carbon from 2.72.3 to 3.1.1 
laravel/framework from v10.43.0 to v11.0.6 
staudenmeir/belongs-to-through from v2.15.1 to v2.16

Laravel Upgrade: from version 10 to 11
Composer Update Changes:

And other Symfony component upgrades as part of the Laravel 11 upgrade requirements.
Given that PHP 8.3 should support the ReflectionFunction::isAnonymous() method, I’m puzzled about the source of this error. Before posting here, I have tried the following steps to resolve the issue:

Checked the PHP version (CLI and web server) to confirm it’s 8.3.1.
Cleared Laravel’s cache (config, cache, and view).
Ran composer update to ensure all dependencies are up to date.
Verified that all required PHP extensions for Laravel 11 are installed and enabled.

I’m looking for insights or suggestions on how to fix this error. Could it be related to a specific package upgrade, or is there something else I’m missing in the Laravel 11 upgrade process?

Thank you in advance for your help!