From b4a7729cb5e09bbd372a8d972d714252be23350a Mon Sep 17 00:00:00 2001
From: Raphael Michel <mail@raphaelmichel.de>
Date: Wed, 14 Oct 2020 18:08:12 +0200
Subject: [PATCH] Fix duplicate invoice cancellation when changing free order
 to paid

---
 src/pretix/base/services/orders.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pretix/base/services/orders.py b/src/pretix/base/services/orders.py
index 0237742e69..6cf5f2bf20 100644
--- a/src/pretix/base/services/orders.py
+++ b/src/pretix/base/services/orders.py
@@ -1884,7 +1884,7 @@ class OrderChangeManager:
     def _reissue_invoice(self):
         i = self.order.invoices.filter(is_cancellation=False).last()
         if self.reissue_invoice and self._invoice_dirty:
-            if i:
+            if i and not i.refered.exists():
                 self._invoices.append(generate_cancellation(i))
             if invoice_qualified(self.order) and \
                 (i or