From d66ae93c932d50e597241bb9bc4a6f1aef53004e Mon Sep 17 00:00:00 2001
From: Sam Bull <git@sambull.org>
Date: Sun, 9 Jul 2023 01:58:10 +0100
Subject: [PATCH] Fix transport is None error (#7333)

Co-authored-by: Sviatoslav Sydorenko <sviat@redhat.com>
(cherry picked from commit 3a54d3785e4b314ca70aaafbee5b3ae8d409c18e)
---
 CHANGES/3355.bugfix  | 1 +
 aiohttp/connector.py | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 CHANGES/3355.bugfix

diff --git a/CHANGES/3355.bugfix b/CHANGES/3355.bugfix
new file mode 100644
index 00000000000..fd002cb00df
--- /dev/null
+++ b/CHANGES/3355.bugfix
@@ -0,0 +1 @@
+Fixed a transport is :data:`None` error -- by :user:`Dreamsorcerer`.
diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index ea58d4cd193..a3a33f549df 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -1130,6 +1130,9 @@ async def _start_tls_connection(
                 f"[{type_err!s}]"
             ) from type_err
         else:
+            if tls_transport is None:
+                msg = "Failed to start TLS (possibly caused by closing transport)"
+                raise client_error(req.connection_key, OSError(msg))
             tls_proto.connection_made(
                 tls_transport
             )  # Kick the state machine of the new TLS protocol