diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index 0fe07438bd0..bc6bececf38 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -292,6 +292,8 @@ defined or can't be applied.
 * Add an early $CFG->session_redis_acquire_lock_warn option
 * Removed $CFG->conversionattemptlimit setting from config.php. assignfeedback_editpdf\task\convert_submissions task
   is now replaced with adhoc tasks with standard fail delay approach.
+* With strftime() being deprecated in PHP 8.1, a new function \core_date::strftime() that can be used as a PHP 8.1-compatible
+  alternative has been introduced.
 
 === 3.11.4 ===
 * A new option dontforcesvgdownload has been added to the $options parameter of the send_file() function.