From e786db028c678f3c5c318318e68d9ade931f1a3b Mon Sep 17 00:00:00 2001
From: Oscar Gustafsson <oscar.gustafsson@gmail.com>
Date: Thu, 9 Mar 2023 17:54:15 +0100
Subject: [PATCH] Print incorrect tz argument in error message

---
 lib/matplotlib/dates.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
index 8f729bff7992..381dd810a5d2 100644
--- a/lib/matplotlib/dates.py
+++ b/lib/matplotlib/dates.py
@@ -230,7 +230,7 @@ def _get_tzinfo(tz=None):
         return tzinfo
     if isinstance(tz, datetime.tzinfo):
         return tz
-    raise TypeError("tz must be string or tzinfo subclass.")
+    raise TypeError(f"tz must be string or tzinfo subclass, not {tz!r}.")
 
 
 # Time-related constants.