Code Sample, a copy-pastable example if possible

>>> import pandas as pd
>>> import datetime as dt
>>> pd.Series([dt.datetime.max.replace(tzinfo=dt.timezone.utc)]).tz_convert('Europe/Berlin')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'datetime.datetime' object is not callable
>>> pd.Series([dt.datetime.max.replace(tzinfo=dt.timezone.utc)]).tz_convert('Europe/Berlin')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/generic.py", line 9703, in tz_convert
    ax = _tz_convert(ax, tz)
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/generic.py", line 9686, in _tz_convert
    "%s is not a valid DatetimeIndex or " "PeriodIndex" % ax_name
TypeError: index is not a valid DatetimeIndex or PeriodIndex
>>> pd.Series([dt.datetime.max.replace(tzinfo=dt.timezone.utc)]).dt.tz_convert('Europe/Berlin')
Traceback (most recent call last):
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 1979, in objects_to_datetime64ns
    values, tz_parsed = conversion.datetime_to_datetime64(data)
  File "pandas/_libs/tslibs/conversion.pyx", line 189, in pandas._libs.tslibs.conversion.datetime_to_datetime64
  File "pandas/_libs/tslibs/conversion.pyx", line 399, in pandas._libs.tslibs.conversion.convert_datetime_to_tsobject
  File "pandas/_libs/tslibs/np_datetime.pyx", line 118, in pandas._libs.tslibs.np_datetime.check_dts_bounds
pandas._libs.tslibs.np_datetime.OutOfBoundsDatetime: Out of bounds nanosecond timestamp: 9999-12-31 23:59:59

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/accessor.py", line 93, in f
    return self._delegate_method(name, *args, **kwargs)
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/indexes/accessors.py", line 106, in _delegate_method
    values = self._get_values()
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/indexes/accessors.py", line 55, in _get_values
    return DatetimeIndex(data, copy=False, name=self.name)
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/indexes/datetimes.py", line 334, in __new__
    int_as_wall_time=True,
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 446, in _from_sequence
    int_as_wall_time=int_as_wall_time,
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 1866, in sequence_to_dt64ns
    data, dayfirst=dayfirst, yearfirst=yearfirst
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 1984, in objects_to_datetime64ns
    raise e
  File "/var/local/conda/envs/pandas-debug/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 1975, in objects_to_datetime64ns
    require_iso8601=require_iso8601,
  File "pandas/_libs/tslib.pyx", line 465, in pandas._libs.tslib.array_to_datetime
  File "pandas/_libs/tslib.pyx", line 543, in pandas._libs.tslib.array_to_datetime
ValueError: Tz-aware datetime.datetime cannot be converted to datetime64 unless utc=True

Problem description

The error message of the outer exception above is misleading. The inner exception has the right error message, but in many cases (e.g. log files) only the outer exception's message is displayed.

If I understand things correctly, the underlying issue is discussed in #12677. In contrast to that ticket I'm fine with getting the exception but would like a clearer message.

Expected Output

The inner exception message should be kept instead of being replaced with a misleading new message.

Output of pd.show_versions()

INSTALLED VERSIONS ------------------ commit : None python : 3.7.4.final.0 python-bits : 64 OS : Linux OS-release : 5.0.0-29-generic machine : x86_64 processor : x86_64 byteorder : little LC_ALL : None LANG : en_US.UTF-8 LOCALE : en_US.UTF-8 pandas : 0.25.1 numpy : 1.16.5 pytz : 2019.2 dateutil : 2.8.0 pip : 19.2.3 setuptools : 41.2.0 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 fastparquet : None gcsfs : None lxml.etree : None matplotlib : None numexpr : None odfpy : None openpyxl : None pandas_gbq : None pyarrow : None pytables : None s3fs : None scipy : None sqlalchemy : None tables : None xarray : None xlrd : None xlwt : None xlsxwriter : None

Comment From: mroeschke

This case doesn't look possible since the original series in now an object type so closing