diff --git a/typo3/sysext/core/Documentation/Changelog/master/Important-84420-ProperlyEscapeReservedCharsInYaml.rst b/typo3/sysext/core/Documentation/Changelog/master/Important-84420-ProperlyEscapeReservedCharsInYaml.rst
new file mode 100644
index 0000000000000000000000000000000000000000..764a4c3ca6e60da05ede3940181c74afef675e30
--- /dev/null
+++ b/typo3/sysext/core/Documentation/Changelog/master/Important-84420-ProperlyEscapeReservedCharsInYaml.rst
@@ -0,0 +1,22 @@
+.. include:: ../../Includes.txt
+
+==========================================================
+Important: #84420 - Properly escape reserved chars in yaml
+==========================================================
+
+See :issue:`84420`
+
+Description
+===========
+
+If dealing with YAML files in the TYPO3 system - for instance to configure forms
+using the `form` extension or if configuring `ckeditor` - integrators should properly
+quote strings containing special characters like `@` or `%` to be upwards compatible
+with the version 4 symfony yaml parser.
+
+More information can be found in the Symfony_ docs.
+
+.. _Symfony:: http://symfony.com/doc/current/components/yaml/yaml_format.html#strings
+
+
+.. index:: Backend, Frontend, ext:form, ext:rte_ckeditor
diff --git a/typo3/sysext/core/Tests/Unit/Configuration/Loader/YamlFileLoaderTest.php b/typo3/sysext/core/Tests/Unit/Configuration/Loader/YamlFileLoaderTest.php
index 783e7d9cda1f92b8e2956d29aa16d51530c9ac6c..b5f508d49be1270b525dbb4550cca3f2ee3f3074 100644
--- a/typo3/sysext/core/Tests/Unit/Configuration/Loader/YamlFileLoaderTest.php
+++ b/typo3/sysext/core/Tests/Unit/Configuration/Loader/YamlFileLoaderTest.php
@@ -106,7 +106,7 @@ firstset:
 options:
     - option1
     - option2
-betterthanbefore: %firstset.myinitialversion%
+betterthanbefore: \'%firstset.myinitialversion%\'
 ';
 
         $expected = [