Depreciate errors and see what needs warning captures

pandas/_libs/tslibs/conversion.pyx

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import warnings
 
 import cython
 from cython import Py_ssize_t
@@ -860,9 +861,13 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
         bint is_coerce = errors == 'coerce', is_raise = errors == 'raise'
 
     # Vectorized version of DstTzInfo.localize
-
     assert is_coerce or is_raise
 
+    if is_coerce:
+        warnings.warn("the errors argument is deprecated, will be removed "
+                      "in a future release. Use the ambiguous or nonexistent "
+                      "argument instead.", DeprecationWarning)
+
     if tz == UTC or tz is None:
         return vals
 

pandas/_libs/tslibs/timestamps.pyx

@@ -930,7 +930,7 @@ class Timestamp(_Timestamp):
             - 'coerce' will return NaT if the timestamp can not be converted
               into the specified timezone
 
-              .. versionadded:: 0.19.0
+              .. depreciated:: 0.24.0
 
         Returns
         -------

pandas/core/arrays/datetimes.py

@@ -661,7 +661,7 @@ def tz_localize(self, tz, ambiguous='raise', nonexistent='raise',
             - 'coerce' will return NaT if the timestamp can not be converted
               to the specified time zone
 
-            .. versionadded:: 0.19.0
+            .. depreciated:: 0.24.0
 
         Returns
         -------