From ee0fc5cc29ad6c7cabbd36edeb5e0355dd98b019 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Fri, 11 Dec 2020 21:43:39 +0100
Subject: [PATCH] Fix AttributeError on reconnect with no retries

Closes #1646.
---
 telethon/network/mtprotosender.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/telethon/network/mtprotosender.py b/telethon/network/mtprotosender.py
index 2eba38e5..581dd43d 100644
--- a/telethon/network/mtprotosender.py
+++ b/telethon/network/mtprotosender.py
@@ -404,7 +404,9 @@ class MTProtoSender:
 
         if not ok:
             self._log.error('Automatic reconnection failed %d time(s)', attempt)
-            await self._disconnect(error=last_error.with_traceback(None))
+            # There may be no error (e.g. automatic reconnection was turned off).
+            error = last_error.with_traceback(None) if last_error else None
+            await self._disconnect(error=error)
 
     def _start_reconnect(self, error):
         """Starts a reconnection in the background."""