From 8dc3383abea72ee3deafec60818aeb817d8fec09 Mon Sep 17 00:00:00 2001
From: Daniel Hollas <daniel.hollas@bristol.ac.uk>
Date: Thu, 3 Jul 2025 10:53:37 +0100
Subject: [PATCH]  gh-135069: Fix exception message in encodings.idna module
 (#135071)

---
 Lib/encodings/idna.py                                          | 2 +-
 .../Library/2025-06-03-12-59-17.gh-issue-135069.xop30V.rst     | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2025-06-03-12-59-17.gh-issue-135069.xop30V.rst

diff --git a/Lib/encodings/idna.py b/Lib/encodings/idna.py
index 60a8d5eb227..0c90b4c9fe1 100644
--- a/Lib/encodings/idna.py
+++ b/Lib/encodings/idna.py
@@ -316,7 +316,7 @@ class IncrementalEncoder(codecs.BufferedIncrementalEncoder):
 class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
     def _buffer_decode(self, input, errors, final):
         if errors != 'strict':
-            raise UnicodeError("Unsupported error handling: {errors}")
+            raise UnicodeError(f"Unsupported error handling: {errors}")
 
         if not input:
             return ("", 0)
diff --git a/Misc/NEWS.d/next/Library/2025-06-03-12-59-17.gh-issue-135069.xop30V.rst b/Misc/NEWS.d/next/Library/2025-06-03-12-59-17.gh-issue-135069.xop30V.rst
new file mode 100644
index 00000000000..1affb5e2aad
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-06-03-12-59-17.gh-issue-135069.xop30V.rst
@@ -0,0 +1,3 @@
+Fix the "Invalid error handling" exception in
+:class:`!encodings.idna.IncrementalDecoder` to correctly replace the
+'errors' parameter.