From f25ecd9bfabe5938897fc1b2f175df506c361d92 Mon Sep 17 00:00:00 2001
From: David Woloszyn <david.woloszyn@moodle.com>
Date: Wed, 19 Apr 2023 12:38:20 +1000
Subject: [PATCH] MDL-77840 backup: Avoid passing nulls to base64_encode

---
 backup/moodle2/backup_custom_fields.php | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/backup/moodle2/backup_custom_fields.php b/backup/moodle2/backup_custom_fields.php
index 2372003b170..cbcb3a6b584 100644
--- a/backup/moodle2/backup_custom_fields.php
+++ b/backup/moodle2/backup_custom_fields.php
@@ -93,6 +93,8 @@ class base64_encode_final_element extends backup_final_element {
      * @param string $value Original value coming from backup step source, usually db.
      */
     public function set_value($value) {
+        // Avoid null being passed to base64_encode.
+        $value = $value ?? '';
         parent::set_value(base64_encode($value));
     }
 }