diff --git a/app/Config/Database.php b/app/Config/Database.php
index 29f6f4a14f42..d7939bc26f9e 100644
--- a/app/Config/Database.php
+++ b/app/Config/Database.php
@@ -182,6 +182,7 @@ class Database extends Config
         'port'        => 3306,
         'foreignKeys' => true,
         'busyTimeout' => 1000,
+        'synchronous' => null,
         'dateFormat'  => [
             'date'     => 'Y-m-d',
             'datetime' => 'Y-m-d H:i:s',
diff --git a/tests/_support/Config/Registrar.php b/tests/_support/Config/Registrar.php
index 43e44de30fc7..8759dcb5a1a2 100644
--- a/tests/_support/Config/Registrar.php
+++ b/tests/_support/Config/Registrar.php
@@ -83,6 +83,7 @@ class Registrar
             'failover'    => [],
             'port'        => 3306,
             'foreignKeys' => true,
+            'synchronous' => 0,
         ],
         'SQLSRV' => [
             'DSN'      => '',
diff --git a/user_guide_src/source/changelogs/v4.6.4.rst b/user_guide_src/source/changelogs/v4.6.4.rst
index 874f439191b7..cc16d924fb03 100644
--- a/user_guide_src/source/changelogs/v4.6.4.rst
+++ b/user_guide_src/source/changelogs/v4.6.4.rst
@@ -22,6 +22,8 @@ Message Changes
 Changes
 *******
 
+- **Config:** Added the ``synchronous`` key for ``Config\Database::$tests``. For SQLite3 driver only.
+
 ************
 Deprecations
 ************
diff --git a/user_guide_src/source/installation/upgrade_464.rst b/user_guide_src/source/installation/upgrade_464.rst
index 70ccdd1017e2..23b9d664fdcf 100644
--- a/user_guide_src/source/installation/upgrade_464.rst
+++ b/user_guide_src/source/installation/upgrade_464.rst
@@ -44,7 +44,8 @@ and it is recommended that you merge the updated versions with your application:
 Config
 ------
 
-- @TODO
+- app/Config/Database.php
+    - Added the ``synchronous`` key for ``Config\Database::$tests``.
 
 All Changes
 ===========