diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index ba77357829..af15797fba 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -3704,6 +3704,8 @@ Editor::abort_reversible_command ()
 	}
 }
 
+#include "pbd/stacktrace.h"
+
 void
 Editor::commit_reversible_command ()
 {
@@ -3716,6 +3718,7 @@ Editor::commit_reversible_command ()
 		}
 
 		if (before.empty()) {
+			PBD::stacktrace(cerr, 30);
 			cerr << "Please call begin_reversible_command() before commit_reversible_command()." << endl;
 		} else {
 			before.pop_back();
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index 18e16e02f6..4a49609193 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -3179,6 +3179,10 @@ void
 Session::add_command (Command* const cmd)
 {
 	assert (_current_trans);
+	if (!_current_trans) {
+		error << "Attempted to add an UNDO command without a current transaction.  ignoring command (" << cmd->name() <<  ")" << endl;
+		return;
+	}
 	DEBUG_UNDO_HISTORY (
 	    string_compose ("Current Undo Transaction %1, adding command: %2",
 	                    _current_trans->name (),