BUG: to_datetime ParserError on incorrect element

[mousey92]

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• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
pd.to_datetime(["today", "yesterday"])

Issue Description

The error message indicates the error on the wrong item to convert.

Converting the string "today" to a datetime is no problem:
pd.to_datetime("today") gives the same result as pd.to_datetime("now")
pd.to_datetime("yesterday") gives
ParserError: Unknown string format: yesterday

But combining the two into
pd.to_datetime(["today", "yesterday"])
gives an error indicating that the "today" string is unknown:

Traceback (most recent call last):
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\arrays\datetimes.py", line 2236, in objects_to_datetime64ns
    values, tz_parsed = conversion.datetime_to_datetime64(data.ravel("K"))
  File "pandas\_libs\tslibs\conversion.pyx", line 360, in pandas._libs.tslibs.conversion.datetime_to_datetime64
TypeError: Unrecognized value type: <class 'str'>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\tools\datetimes.py", line 1076, in to_datetime
    result = convert_listlike(arg, format)
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\tools\datetimes.py", line 402, in _convert_listlike_datetimes
    result, tz_parsed = objects_to_datetime64ns(
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\arrays\datetimes.py", line 2242, in objects_to_datetime64ns
    raise err
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\arrays\datetimes.py", line 2224, in objects_to_datetime64ns
    result, tz_parsed = tslib.array_to_datetime(
  File "pandas\_libs\tslib.pyx", line 381, in pandas._libs.tslib.array_to_datetime
  File "pandas\_libs\tslib.pyx", line 613, in pandas._libs.tslib.array_to_datetime
  File "pandas\_libs\tslib.pyx", line 751, in pandas._libs.tslib._array_to_datetime_object
  File "pandas\_libs\tslib.pyx", line 742, in pandas._libs.tslib._array_to_datetime_object
  File "pandas\_libs\tslibs\parsing.pyx", line 281, in pandas._libs.tslibs.parsing.parse_datetime_string
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\dateutil\parser\_parser.py", line 1368, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\dateutil\parser\_parser.py", line 643, in parse
    raise ParserError("Unknown string format: %s", timestr)
dateutil.parser._parser.ParserError: Unknown string format: today

Obviously the "today" string is not the problem, it's the "yesterday" string

Switching the two strings around does gives the proper error:
pd.to_datetime(["yesterday", "today"])
gives

Traceback (most recent call last):
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\arrays\datetimes.py", line 2236, in objects_to_datetime64ns
    values, tz_parsed = conversion.datetime_to_datetime64(data.ravel("K"))
  File "pandas\_libs\tslibs\conversion.pyx", line 360, in pandas._libs.tslibs.conversion.datetime_to_datetime64
TypeError: Unrecognized value type: <class 'str'>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\tools\datetimes.py", line 1076, in to_datetime
    result = convert_listlike(arg, format)
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\tools\datetimes.py", line 402, in _convert_listlike_datetimes
    result, tz_parsed = objects_to_datetime64ns(
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\arrays\datetimes.py", line 2242, in objects_to_datetime64ns
    raise err
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\pandas\core\arrays\datetimes.py", line 2224, in objects_to_datetime64ns
    result, tz_parsed = tslib.array_to_datetime(
  File "pandas\_libs\tslib.pyx", line 381, in pandas._libs.tslib.array_to_datetime
  File "pandas\_libs\tslib.pyx", line 613, in pandas._libs.tslib.array_to_datetime
  File "pandas\_libs\tslib.pyx", line 751, in pandas._libs.tslib._array_to_datetime_object
  File "pandas\_libs\tslib.pyx", line 742, in pandas._libs.tslib._array_to_datetime_object
  File "pandas\_libs\tslibs\parsing.pyx", line 281, in pandas._libs.tslibs.parsing.parse_datetime_string
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\dateutil\parser\_parser.py", line 1368, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "C:\Users\Matthijs.Kramer\Anaconda3\envs\test\lib\site-packages\dateutil\parser\_parser.py", line 643, in parse
    raise ParserError("Unknown string format: %s", timestr)
dateutil.parser._parser.ParserError: Unknown string format: yesterday

It seems whenever any of the input strings cannot be parsed, an error is thrown on the first item in the input.

Expected Behavior

When providing an number of datetime strings to pd.to_datetime, not all of which can be parsed, the error message should indicate on which string the error occurred, rather than the first string in the list.

In the above example, the error message should read
Unknown string format: yesterday instead of Unknown string format: today, regardless of the order of the two input strings

Installed Versions

INSTALLED VERSIONS

commit : e8093ba
python : 3.10.5.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19044
machine : AMD64
processor : Intel64 Family 6 Model 158 Stepping 13, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_Netherlands.1252

pandas : 1.4.3
numpy : 1.23.0
pytz : 2022.1
dateutil : 2.8.2
setuptools : 62.6.0
pip : 22.1.2
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : None
IPython : None
pandas_datareader: None
bs4 : None
bottleneck : None
brotli : None
fastparquet : None
fsspec : None
gcsfs : None
markupsafe : None
matplotlib : None
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : None
snappy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
zstandard : None

[simonjayhawkins]

thanks @mousey92 for the report.

#16757 and #46509 are similar in that they both relate to the clarity of the error messages but will leave this one open for now.

contributions and PRs to fix welcome

[sidshrivastav]

@simonjayhawkins hey I've tried to debug this issue, this message is coming from dateutil parser, I believe we handle cases for now and today in tslib, maybe we need to add check if there in parser if data contain anything other than now and today, throw an error instead of letting it go to dateutil.parser