Reset `WCF::AVAILABLE_UPGRADE_VERSION` for 6.0

diff --git a/wcfsetup/install/files/lib/system/WCF.class.php b/wcfsetup/install/files/lib/system/WCF.class.php
index f60f4a76a969a299cd197e4ce576b4b237f47edb..df185b97e3bb2ba31731ce555ac82682f4b9a145 100644 (file)
--- a/wcfsetup/install/files/lib/system/WCF.class.php
+++ b/wcfsetup/install/files/lib/system/WCF.class.php
@@ -107,7 +107,7 @@ class WCF
      * @var ?string
      * @since 5.3
      */
-    public const AVAILABLE_UPGRADE_VERSION = '6.0';
+    public const AVAILABLE_UPGRADE_VERSION = null;
 
     /**
      * list of currently loaded applications