changed all na to np.nan

Author: debnathshoham

pandas/_libs/tslibs/strptime.pyx

@@ -134,7 +134,7 @@ def array_strptime(ndarray[object] values, object fmt, bint exact=True, errors='
                 iresult[i] = NPY_NAT
                 continue
         else:
-            if checknull_with_nat(val) or val.__repr__() == "<NA>":
+            if checknull_with_nat(val):
                 iresult[i] = NPY_NAT
                 continue
             else:

pandas/core/tools/datetimes.py

@@ -56,7 +56,10 @@
     ABCDataFrame,
     ABCSeries,
 )
-from pandas.core.dtypes.missing import notna
+from pandas.core.dtypes.missing import (
+    isna,
+    notna,
+)
 
 from pandas.arrays import (
     DatetimeArray,
@@ -496,6 +499,8 @@ def _to_datetime_with_format(
                 utc = tz == "utc"
                 return _box_as_indexlike(result, utc=utc, name=name)
 
+        # GH#42957 #replacing all na with np.nan
+        arg[isna(arg)] = np.nan
         # fallback
         res = _array_strptime_with_fallback(
             arg, name, tz, fmt, exact, errors, infer_datetime_format