500 Errors from rest calls (primarily)

[JamesFX2]

We've implemented this on our production environment (Magento 2.4.7-p8) and we're getting occasional errors like,

[2026-01-23T16:47:56.061976+00:00] main.CRITICAL: Warning: Undefined array key "adminhtml" in /home/cloudpanel/htdocs/2026_01_22_3_06_02_branch_m2.4.7-058-Eye-Of-The-Tiger-v2/vendor/colinmollenhour/php-redis-session-abstract/src/Cm/RedisSession/Handler.php on line 975 [] []

That relates to

    /**
     * Remove array elements by key recursively (deep down first and removing empty arrays)
     *
     * @param array $arr1
     * @param array $arr2
     * @return array
     */
    protected function _arrayRemoveRecursive($arr1, $arr2)
    {
        foreach ($arr2 as $key => $item) {
            if (is_array($arr2[$key])) {
                $arr1[$key] = $this->_arrayRemoveRecursive($arr1[$key], $arr2[$key]);

                if (count($arr1[$key]) === 0) {
                    unset($arr1[$key]);
                }
            } else {
                unset($arr1[$key]);
            }
        }

        return $arr1;
    }

I'd also request that you please flag up in the README that implementing this on live without clearing all sessions will cause issues - anyone who had sessions before implementation will have issues because their previous data cannot be unserialized.