From b6e1f847401b2affd88b30d85f2f649f4e8b0f9e Mon Sep 17 00:00:00 2001
From: YueGuobin <yueguobin@outlook.com>
Date: Wed, 3 Jun 2026 12:18:28 +0800
Subject: [PATCH] Move running project check before fast duplication

Move the is_running() check from _fast_duplication() to
duplicate() to avoid the error message being wrapped by
the except Exception handler. This ensures the error
message is clean and prevents wasted fast duplication
attempts on running projects.
---
 gns3server/controller/project.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gns3server/controller/project.py b/gns3server/controller/project.py
index 0526df838..aa3b361e1 100644
--- a/gns3server/controller/project.py
+++ b/gns3server/controller/project.py
@@ -1334,6 +1334,9 @@ class Project:
         self.dump()
         assert self._status != "closed"
 
+        if self.is_running():
+            raise ControllerError("Project must be stopped in order to duplicate it")
+
         try:
             proj = await self._fast_duplication(name, reset_mac_addresses)
             if proj: