Added improvements in to_datetime Error reporting message - incorrect field today/now shown in error

pandas/_libs/tslib.pyx

@@ -799,6 +799,7 @@ cdef _array_to_datetime_object(
     # We return an object array and only attempt to parse:
     # 1) NaT or NaT-like values
     # 2) datetime strings, which we return as datetime.datetime
+    # 3) special strings - "now" & "today"
     for i in range(n):
         val = values[i]
         if checknull_with_nat_and_na(val) or PyDateTime_Check(val):
@@ -817,7 +818,8 @@ cdef _array_to_datetime_object(
                                                    yearfirst=yearfirst)
                 pydatetime_to_dt64(oresult[i], &dts)
                 check_dts_bounds(&dts)
-            except (ValueError, OverflowError):
+            except (ValueError, OverflowError) as ex:
+                ex.args = (f"{ex} present at position {i}", )
                 if is_coerce:
                     oresult[i] = <object>NaT
                     continue

pandas/_libs/tslibs/parsing.pyx

@@ -63,6 +63,7 @@ from pandas._libs.tslibs.util cimport (
     get_c_string_buf_and_size,
     is_array,
 )
+from pandas._libs.tslibs.timestamps import Timestamp
 
 
 cdef extern from "../src/headers/portable.h":
@@ -298,6 +299,11 @@ def parse_datetime_string(
     if dt is not None:
         return dt
 
+    # Handling special case strings today & now
+    dt = _parse_today_now(date_string)
+    if dt is not None:
+        return dt
+
     try:
         dt, _ = _parse_dateabbr_string(date_string, _DEFAULT_DATETIME, freq=None)
         return dt
@@ -1210,3 +1216,25 @@ cpdef str get_rule_month(str source):
         return "DEC"
     else:
         return source.split("-")[1]
+
+cdef inline object _parse_today_now(str date_string):
+    """
+    Parse special case date inputs - "today", "now"
+    and if present return corresponding datetime object
+
+    Parameters
+    ----------
+    date_string : str
+
+    Returns:
+    --------
+    datetime or None
+    """
+    cdef:
+        object res = None
+
+    if date_string == "now":
+        res = Timestamp.utcnow()
+    elif date_string == "today":
+        res = Timestamp.today()
+    return res

pandas/tests/tools/test_to_datetime.py

@@ -2591,6 +2591,13 @@ def test_invalid_origins_tzinfo(self):
         with pytest.raises(ValueError, match="must be tz-naive"):
             to_datetime(1, unit="D", origin=datetime(2000, 1, 1, tzinfo=pytz.utc))
 
+    def test_incorrect_value_exception(self):
+        # GH47495
+        with pytest.raises(
+            ValueError, match="Unknown string format: yesterday present at position 1"
+        ):
+            to_datetime(["today", "yesterday"])
+
     @pytest.mark.parametrize("format", [None, "%Y-%m-%d %H:%M:%S"])
     def test_to_datetime_out_of_bounds_with_format_arg(self, format):
         # see gh-23830