From c5f7d7abaf6d9cae5a394d096da4e1a374978f0e Mon Sep 17 00:00:00 2001
From: Muhammad Arnaldo <muhammad.arnaldo@gmail.com>
Date: Thu, 5 Mar 2026 14:09:26 +0700
Subject: [PATCH] MDL-87438 core: Fix multiselect saving with empty choices

---
 public/lib/adminlib.php | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/public/lib/adminlib.php b/public/lib/adminlib.php
index c68705c8cf2..4a86a77c351 100644
--- a/public/lib/adminlib.php
+++ b/public/lib/adminlib.php
@@ -3707,12 +3707,15 @@ class admin_setting_configmultiselect extends admin_setting_configselect {
         if (!is_array($data)) {
             return ''; //ignore it
         }
-        if (!$this->load_choices() or empty($this->choices)) {
-            return '';
-        }
 
         unset($data['xxxxx']);
 
+        // Only reject when the caller actually supplied a value
+        // and there is no valid choices to validate against.
+        if (!empty($data) && (!$this->load_choices() || empty($this->choices))) {
+            return '';
+        }
+
         $save = array();
         foreach ($data as $value) {
             if (!array_key_exists($value, $this->choices)) {