From 89758d7e16a7c343a48875712eec7a04a50e3d77 Mon Sep 17 00:00:00 2001
From: kenjis <kenji.uui@gmail.com>
Date: Wed, 13 Sep 2023 11:34:14 +0900
Subject: [PATCH] docs: add description of incompatible behavior

---
 user_guide_src/source/installation/upgrade_validations.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/user_guide_src/source/installation/upgrade_validations.rst b/user_guide_src/source/installation/upgrade_validations.rst
index acc093a94580..8343b989a699 100644
--- a/user_guide_src/source/installation/upgrade_validations.rst
+++ b/user_guide_src/source/installation/upgrade_validations.rst
@@ -18,6 +18,8 @@ What has been changed
   Use :ref:`Rule Classes <validation-using-rule-classes>` or
   :ref:`Closure Rule <validation-using-closure-rule>`
   instead.
+- In CI3, Callbacks/Callable rules were prioritized, but in CI4, Closure Rules are
+  not prioritized, and are checked in the order in which they are listed.
 - CI4 validation format rules do not permit empty string.
 - CI4 validation never changes your data.
 - Since v4.3.0, :php:func:`validation_errors()` has been introduced, but the API is different from CI3's.