From d44f1c65239c3e33509224aa1931631243dbfa7f Mon Sep 17 00:00:00 2001
From: Tero Vuotila <tero.vuotila@falcony.io>
Date: Wed, 16 Jul 2025 12:21:50 +0300
Subject: [PATCH] relax type hint for bytes io

---
 CHANGES.rst          | 1 +
 src/flask/helpers.py | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index 1c41e34b..a5761bc2 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -5,6 +5,7 @@ Unreleased
 
 -   When using ``follow_redirects`` in the test client, the final state
     of ``session`` is correct. :issue:`5786`
+-   Relax type hint for passing bytes IO to ``send_file``. :issue:`5776`
 
 
 Version 3.1.1
diff --git a/src/flask/helpers.py b/src/flask/helpers.py
index 90a0e0c6..081548a9 100644
--- a/src/flask/helpers.py
+++ b/src/flask/helpers.py
@@ -398,7 +398,7 @@ def _prepare_send_file_kwargs(**kwargs: t.Any) -> dict[str, t.Any]:
 
 
 def send_file(
-    path_or_file: os.PathLike[t.AnyStr] | str | t.BinaryIO,
+    path_or_file: os.PathLike[t.AnyStr] | str | t.IO[bytes],
     mimetype: str | None = None,
     as_attachment: bool = False,
     download_name: str | None = None,