Fixes Error thrown when None is passed to pd.to_datetime() with format as %Y%m%d (pandas-dev#30083)

Author: maheshrbapatu

doc/source/whatsnew/v1.0.0.rst

@@ -693,6 +693,7 @@ Datetimelike
 - Bug in :meth:`Series.var` failing to raise ``TypeError`` when called with ``timedelta64[ns]`` dtype (:issue:`28289`)
 - Bug in :meth:`DatetimeIndex.strftime` and :meth:`Series.dt.strftime` where ``NaT`` was converted to the string ``'NaT'`` instead of ``np.nan`` (:issue:`29578`)
 - Bug in :attr:`Timestamp.resolution` being a property instead of a class attribute (:issue:`29910`)
+- Bug in :func:`pandas.to_datetime` when called with ``None`` raising ``TypeError`` instead of returning ``NaT`` (:issue:`30011`)
 
 Timedelta
 ^^^^^^^^^

pandas/core/tools/datetimes.py

@@ -883,21 +883,21 @@ def calc_with_mask(carg, mask):
     # try intlike / strings that are ints
     try:
         return calc(arg.astype(np.int64))
-    except (ValueError, OverflowError):
+    except (ValueError, OverflowError, TypeError):
         pass
 
     # a float with actual np.nan
     try:
         carg = arg.astype(np.float64)
         return calc_with_mask(carg, notna(carg))
-    except (ValueError, OverflowError):
+    except (ValueError, OverflowError, TypeError):
         pass
 
     # string with NaN-like
     try:
         mask = ~algorithms.isin(arg, list(tslib.nat_strings))
         return calc_with_mask(arg, mask)
-    except (ValueError, OverflowError):
+    except (ValueError, OverflowError, TypeError):
         pass
 
     return None

pandas/tests/indexes/datetimes/test_tools.py

@@ -101,6 +101,29 @@ def test_to_datetime_format_YYYYMMDD(self, cache):
         expected = Series(["20121231", "20141231", "NaT"], dtype="M8[ns]")
         tm.assert_series_equal(result, expected)
 
+    @pytest.mark.parametrize(
+        "input_s",
+        [
+            # Null values with Strings
+            ["19801222", "20010112", None],
+            ["19801222", "20010112", np.nan],
+            ["19801222", "20010112", pd.NaT],
+            ["19801222", "20010112", "NaT"],
+            # Null values with Integers
+            [19801222, 20010112, None],
+            [19801222, 20010112, np.nan],
+            [19801222, 20010112, pd.NaT],
+            [19801222, 20010112, "NaT"],
+        ],
+    )
+    def test_to_datetime_format_YYYYMMDD_with_none(self, input_s):
+        # GH 30011
+        # format='%Y%m%d'
+        # with None
+        expected = Series([Timestamp("19801222"), Timestamp("20010112"), pd.NaT])
+        result = Series(pd.to_datetime(input_s, format="%Y%m%d"))
+        tm.assert_series_equal(result, expected)
+
     @pytest.mark.parametrize(
         "input_s, expected",
         [