From 279cbb2b80b55cc55c6c0a69248620bfaf51bf59 Mon Sep 17 00:00:00 2001
From: MarcoGorelli <>
Date: Mon, 16 Jan 2023 10:43:13 +0000
Subject: [PATCH 1/2] pass unit to validate_frequency

---
 pandas/core/arrays/datetimes.py           |  2 +-
 pandas/tests/frame/methods/test_asfreq.py | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index f1da99825d5fd..e276861f3f4ca 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -357,7 +357,7 @@ def _from_sequence_not_strict(
 
         if inferred_freq is None and freq is not None:
             # this condition precludes `freq_infer`
-            cls._validate_frequency(result, freq, ambiguous=ambiguous)
+            cls._validate_frequency(result, freq, ambiguous=ambiguous, unit=result.unit)
 
         elif freq_infer:
             # Set _freq directly to bypass duplicative _validate_frequency
diff --git a/pandas/tests/frame/methods/test_asfreq.py b/pandas/tests/frame/methods/test_asfreq.py
index 5b3e1614e1ada..9fa9f27e7e312 100644
--- a/pandas/tests/frame/methods/test_asfreq.py
+++ b/pandas/tests/frame/methods/test_asfreq.py
@@ -17,6 +17,10 @@
 
 
 class TestAsFreq:
+    @pytest.fixture(params=["s", "ms", "us", "ns"])
+    def unit(self, request):
+        return request.param
+
     def test_asfreq2(self, frame_or_series):
         ts = frame_or_series(
             [0.0, 1.0, 2.0],
@@ -197,3 +201,11 @@ def test_asfreq_with_unsorted_index(self, frame_or_series):
 
         result = result.asfreq("D")
         tm.assert_equal(result, expected)
+
+    def test_asfreq_after_normalize(self, unit):
+        # https://github.com/pandas-dev/pandas/issues/50727
+        result = DatetimeIndex(
+            date_range("2000", periods=2).as_unit(unit).normalize(), freq="D"
+        )
+        expected = DatetimeIndex(["2000-01-01", "2000-01-02"], freq="D").as_unit(unit)
+        tm.assert_index_equal(result, expected)

From 4f152fce64322427db7b4af9241cf57e9e21630c Mon Sep 17 00:00:00 2001
From: MarcoGorelli <>
Date: Tue, 17 Jan 2023 11:13:37 +0000
Subject: [PATCH 2/2] set unit within _validate_frequency

---
 pandas/core/arrays/datetimelike.py | 7 ++++++-
 pandas/core/arrays/datetimes.py    | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
index bb21bed2dc779..816d8abec1428 100644
--- a/pandas/core/arrays/datetimelike.py
+++ b/pandas/core/arrays/datetimelike.py
@@ -1897,7 +1897,12 @@ def _validate_frequency(cls, index, freq, **kwargs):
 
         try:
             on_freq = cls._generate_range(
-                start=index[0], end=None, periods=len(index), freq=freq, **kwargs
+                start=index[0],
+                end=None,
+                periods=len(index),
+                freq=freq,
+                unit=index.unit,
+                **kwargs,
             )
             if not np.array_equal(index.asi8, on_freq.asi8):
                 raise ValueError
diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
index 5cc87cdde8ebc..2c1ef7f05fa03 100644
--- a/pandas/core/arrays/datetimes.py
+++ b/pandas/core/arrays/datetimes.py
@@ -357,7 +357,7 @@ def _from_sequence_not_strict(
 
         if inferred_freq is None and freq is not None:
             # this condition precludes `freq_infer`
-            cls._validate_frequency(result, freq, ambiguous=ambiguous, unit=result.unit)
+            cls._validate_frequency(result, freq, ambiguous=ambiguous)
 
         elif freq_infer:
             # Set _freq directly to bypass duplicative _validate_frequency