diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index 88be372ca4..13b176538d 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -3,7 +3,7 @@
  * Copyright (C) 2007-2012 Carl Hetherington <carl@carlh.net>
  * Copyright (C) 2007-2014 David Robillard <d@drobilla.net>
  * Copyright (C) 2008-2009 Sampo Savolainen <v2@iki.fi>
- * Copyright (C) 2013-2019 Robin Gareus <robin@gareus.org>
+ * Copyright (C) 2013-2023 Robin Gareus <robin@gareus.org>
  * Copyright (C) 2016-2017 Tim Mayberry <mojofunk@gmail.com>
  * Copyright (C) 2018 Johannes Mueller <github@johannes-mueller.org>
  *
@@ -2824,6 +2824,14 @@ PluginInsert::set_state(const XMLNode& node, int version)
 		}
 	}
 
+	if (version < 7002 && !_custom_cfg /* && !strict_io ()*/ && plugin()->get_info ()->type == ARDOUR::VST3) {
+		if (_configured_in != plugin()->get_info()->n_inputs * _plugins.size () ||
+		    _configured_out != plugin()->get_info()->n_outputs * _plugins.size ()) {
+			/* do not add VST busses which were not previously available */
+			_custom_cfg = true;
+		}
+	}
+
 	if (in_maps == out_maps && out_maps >0 && out_maps == get_count()) {
 		_maps_from_state = true;
 	}
diff --git a/libs/ardour/wscript b/libs/ardour/wscript
index fb001afce5..e3428f76ae 100644
--- a/libs/ardour/wscript
+++ b/libs/ardour/wscript
@@ -8,7 +8,7 @@ import subprocess
 import sys
 
 # default state file version for this build
-CURRENT_SESSION_FILE_VERSION = 7001
+CURRENT_SESSION_FILE_VERSION = 7002
 
 I18N_PACKAGE = 'ardour'