TypeError: to_datetime() got multiple values for argument 'errors'
I find it necessary to specify an explicit date parser when reading certain CSV files because `read_csv(..., error_bad_lines=True)` does not recognize errors that fall within the index column; it falls back to string-indexing instead. I've dealt with this by specifying `coerce=True`, but that method is deprecated since #10653 combined the `coerce` and `errors` keywords. Now, neither method appears to work for me.

Here is the test snippet:

``` python
import pandas as pd
try:
    from StringIO import StringIO
except ImportError:
    from io import StringIO

fakefile = """\
"TOA5","indoorair(1.2.3)","CR1000","47257","CR1000.Std.28.02","CPU:indoorair.cr1","37538","tsdata"
"TIMESTAMP","RECORD","dc1100_pm_small","dc1100_pm_large","li840a_CO2","li840a_H2O","li840a_cell_T","li840a_cell_P","li840a_dew_T","li840a_pwr_src","typeK_amb_T","logger_panel_T"
"TS","RN","counts/m^3","counts/m^3","ppmv","ppthv","degC","mbar","degC","Vdc","degC","degC"
"","","Smp","Smp","Avg","Avg","Avg","Avg","Avg","Avg","Avg","Avg"
"2016-04-06 13:20:00",5756,1373740,42377,1149.936,10.30014,51.20879,928.455,6.267447,24.1189,21.4,25.93
"2016-04-06 13:21:00",5757,1437306,56503,1147.533,10.30781,51.20538,928.4556,6.278251,24.1182,21.43,25.94
"2016-04-06 13:22:00",5758,1454964,49440,1146.63,10.31073,51.20726,928.449,6.282249,24.11856,21.43,25.95
"2016-04-06 13:23:00",5759,1433775,52972,1145.948,10.30542,51.2077,928.4606,6.274971,24.11839,21.4,25.94
"2016-04-06 13:24:00",5760,1483216,56503,1145.541,10.30182,51.20682,928.451,6.26975,24.11856,21.4,25.95"""

df = pd.read_csv(StringIO(fakefile),
                 index_col=0,
                 parse_dates=True,
                 date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
                                                       errors='coerce'),
                 header=1,
                 skiprows=[2,3],
                 na_values=['NAN', -7999, 7999], 
                 keep_default_na=False)
```
#### Machine 1

Here's the traceback I received on my Linux Mint box (before reducing to MWE): 

```
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-11-dca3f9d3edf1> in <module>()
----> 1 indoor_air = read_TOA5('pullman04/winter16/indoor-rack/indoor-air_tsdata.dat')

<ipython-input-10-406a7964b57c> in read_TOA5(fpath)
     12                      # https://s.campbellsci.com/documents/us/manuals/cr1000.pdf
     13                      ## HINT csv parser consumes the dbl-quotes around NANs
---> 14                      na_values=['NAN', -7999, 7999], keep_default_na=False)
     15     #if len(df.index.get_duplicates()): # if dup rows found
     16     #    df = df.groupby(level=0).first() # discard copies

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in parser_f(filepath_or_buffer, sep, delimiter, header, names, index_col, usecols, squeeze, prefix, mangle_dupe_cols, dtype, engine, converters, true_values, false_values, skipinitialspace, skiprows, skipfooter, nrows, na_values, keep_default_na, na_filter, verbose, skip_blank_lines, parse_dates, infer_datetime_format, keep_date_col, date_parser, dayfirst, iterator, chunksize, compression, thousands, decimal, lineterminator, quotechar, quoting, escapechar, comment, encoding, dialect, tupleize_cols, error_bad_lines, warn_bad_lines, skip_footer, doublequote, delim_whitespace, as_recarray, compact_ints, use_unsigned, low_memory, buffer_lines, memory_map, float_precision)
    560                     skip_blank_lines=skip_blank_lines)
    561 
--> 562         return _read(filepath_or_buffer, kwds)
    563 
    564     parser_f.__name__ = name

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in _read(filepath_or_buffer, kwds)
    323         return parser
    324 
--> 325     return parser.read()
    326 
    327 _parser_defaults = {

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in read(self, nrows)
    813                 raise ValueError('skip_footer not supported for iteration')
    814 
--> 815         ret = self._engine.read(nrows)
    816 
    817         if self.options.get('as_recarray'):

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in read(self, nrows)
   1385 
   1386             names, data = self._do_date_conversions(names, data)
-> 1387             index, names = self._make_index(data, alldata, names)
   1388 
   1389         # maybe create a mi on the columns

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in _make_index(self, data, alldata, columns, indexnamerow)
   1028         elif not self._has_complex_date_col:
   1029             index = self._get_simple_index(alldata, columns)
-> 1030             index = self._agg_index(index)
   1031 
   1032         elif self._has_complex_date_col:

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in _agg_index(self, index, try_parse_dates)
   1109 
   1110             if (try_parse_dates and self._should_parse_dates(i)):
-> 1111                 arr = self._date_conv(arr)
   1112 
   1113             col_na_values = self.na_values

/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.pyc in converter(*date_cols)
   2286                         errors='ignore')
   2287                 except Exception:
-> 2288                     return generic_parser(date_parser, *date_cols)
   2289 
   2290     return converter

/usr/local/lib/python2.7/dist-packages/pandas/io/date_converters.pyc in generic_parser(parse_func, *cols)
     36     for i in range(N):
     37         args = [c[i] for c in cols]
---> 38         results[i] = parse_func(*args)
     39 
     40     return results

<ipython-input-10-406a7964b57c> in <lambda>(ts)
      6                      # explicit parser + coerce to prevent fallback to string-indexing
      7                      date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
----> 8                                                            errors='coerce'),
      9                      header=1, # 1st line metadata 2nd headers
     10                      skiprows=[2,3], # 3rd units 4th agg type

/usr/local/lib/python2.7/dist-packages/pandas/util/decorators.pyc in wrapper(*args, **kwargs)
     89                 else:
     90                     kwargs[new_arg_name] = new_arg_value
---> 91             return func(*args, **kwargs)
     92         return wrapper
     93     return _deprecate_kwarg

TypeError: to_datetime() got multiple values for keyword argument 'errors'
```

using pandas 0.18.1 (freshly updated) with Python 2.7 (_Sorry, I don't have `pd.show_versions()` output..._)
#### Machine 2

When I run the same snippet on Windows 7 with pandas 0.18.1, Python 3.5.1:

```
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in converter(*date_cols)
   2275                 result = tools.to_datetime(
-> 2276                     date_parser(*date_cols), errors='ignore')
   2277                 if isinstance(result, datetime.datetime):

<ipython-input-11-5805c9b0f012> in <lambda>(ts)
      4                  date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
----> 5                                                        errors='coerce'),
      6                  header=1,

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py in wrapper(*args, **kwargs)
     90                     kwargs[new_arg_name] = new_arg_value
---> 91             return func(*args, **kwargs)
     92         return wrapper

TypeError: to_datetime() got multiple values for argument 'errors'

During handling of the above exception, another exception occurred:

TypeError                                 Traceback (most recent call last)
C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in converter(*date_cols)
   2284                                             parser=date_parser,
-> 2285                                             dayfirst=dayfirst),
   2286                         errors='ignore')

pandas\src\inference.pyx in pandas.lib.try_parse_dates (pandas\lib.c:57884)()

pandas\src\inference.pyx in pandas.lib.try_parse_dates (pandas\lib.c:57802)()

<ipython-input-11-5805c9b0f012> in <lambda>(ts)
      4                  date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
----> 5                                                        errors='coerce'),
      6                  header=1,

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py in wrapper(*args, **kwargs)
     90                     kwargs[new_arg_name] = new_arg_value
---> 91             return func(*args, **kwargs)
     92         return wrapper

TypeError: to_datetime() got multiple values for argument 'errors'

During handling of the above exception, another exception occurred:

TypeError                                 Traceback (most recent call last)
<ipython-input-11-5805c9b0f012> in <module>()
      7                  skiprows=[2,3],
      8                  na_values=['NAN', -7999, 7999],
----> 9                  keep_default_na=False)
     10 df

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in parser_f(filepath_or_buffer, sep, delimiter, header, names, index_col, usecols, squeeze, prefix, mangle_dupe_cols, dtype, engine, converters, true_values, false_values, skipinitialspace, skiprows, skipfooter, nrows, na_values, keep_default_na, na_filter, verbose, skip_blank_lines, parse_dates, infer_datetime_format, keep_date_col, date_parser, dayfirst, iterator, chunksize, compression, thousands, decimal, lineterminator, quotechar, quoting, escapechar, comment, encoding, dialect, tupleize_cols, error_bad_lines, warn_bad_lines, skip_footer, doublequote, delim_whitespace, as_recarray, compact_ints, use_unsigned, low_memory, buffer_lines, memory_map, float_precision)
    560                     skip_blank_lines=skip_blank_lines)
    561 
--> 562         return _read(filepath_or_buffer, kwds)
    563 
    564     parser_f.__name__ = name

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in _read(filepath_or_buffer, kwds)
    323         return parser
    324 
--> 325     return parser.read()
    326 
    327 _parser_defaults = {

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in read(self, nrows)
    813                 raise ValueError('skip_footer not supported for iteration')
    814 
--> 815         ret = self._engine.read(nrows)
    816 
    817         if self.options.get('as_recarray'):

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in read(self, nrows)
   1385 
   1386             names, data = self._do_date_conversions(names, data)
-> 1387             index, names = self._make_index(data, alldata, names)
   1388 
   1389         # maybe create a mi on the columns

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in _make_index(self, data, alldata, columns, indexnamerow)
   1028         elif not self._has_complex_date_col:
   1029             index = self._get_simple_index(alldata, columns)
-> 1030             index = self._agg_index(index)
   1031 
   1032         elif self._has_complex_date_col:

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in _agg_index(self, index, try_parse_dates)
   1109 
   1110             if (try_parse_dates and self._should_parse_dates(i)):
-> 1111                 arr = self._date_conv(arr)
   1112 
   1113             col_na_values = self.na_values

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py in converter(*date_cols)
   2286                         errors='ignore')
   2287                 except Exception:
-> 2288                     return generic_parser(date_parser, *date_cols)
   2289 
   2290     return converter

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\date_converters.py in generic_parser(parse_func, *cols)
     36     for i in range(N):
     37         args = [c[i] for c in cols]
---> 38         results[i] = parse_func(*args)
     39 
     40     return results

<ipython-input-11-5805c9b0f012> in <lambda>(ts)
      3                  parse_dates=True,
      4                  date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
----> 5                                                        errors='coerce'),
      6                  header=1,
      7                  skiprows=[2,3],

C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py in wrapper(*args, **kwargs)
     89                 else:
     90                     kwargs[new_arg_name] = new_arg_value
---> 91             return func(*args, **kwargs)
     92         return wrapper
     93     return _deprecate_kwarg

TypeError: to_datetime() got multiple values for argument 'errors'
```

```
INSTALLED VERSIONS
------------------
commit: None
python: 3.5.1.final.0
python-bits: 64
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 23 Stepping 10, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.18.1
nose: 1.3.7
pip: 8.1.2
setuptools: 23.0.0
Cython: 0.24
numpy: 1.11.0
scipy: 0.17.1
statsmodels: 0.6.1
xarray: None
IPython: 4.2.0
sphinx: 1.3.1
patsy: 0.4.1
dateutil: 2.5.3
pytz: 2016.4
blosc: None
bottleneck: 1.0.0
tables: 3.2.2
numexpr: 2.6.0
matplotlib: 1.5.1
openpyxl: 2.3.2
xlrd: 1.0.0
xlwt: 1.1.2
xlsxwriter: 0.9.2
lxml: 3.6.0
bs4: 4.4.1
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.13
pymysql: None
psycopg2: None
jinja2: 2.8
boto: 2.40.0
pandas_datareader: None
```
#### Machine 2 (again)

Strangely, I get the same error using a different (older) distribution on the same Win7 machine:

```
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-1-4ac37d43a03f> in <module>()
     23                  skiprows=[2,3],
     24                  na_values=['NAN', -7999, 7999],
---> 25                  keep_default_na=False)

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in parser_f(filepath_or_buffer, sep, dialect, compression, doublequote, escapechar, quotechar, quoting, skipinitialspace, lineterminator, header, index_col, names, prefix, skiprows, skipfooter, skip_footer, na_values, na_fvalues, true_values, false_values, delimiter, converters, dtype, usecols, engine, delim_whitespace, as_recarray, na_filter, compact_ints, use_unsigned, low_memory, buffer_lines, warn_bad_lines, error_bad_lines, keep_default_na, thousands, comment, decimal, parse_dates, keep_date_col, dayfirst, date_parser, memory_map, float_precision, nrows, iterator, chunksize, verbose, encoding, squeeze, mangle_dupe_cols, tupleize_cols, infer_datetime_format, skip_blank_lines)
    463                     skip_blank_lines=skip_blank_lines)
    464 
--> 465         return _read(filepath_or_buffer, kwds)
    466 
    467     parser_f.__name__ = name

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in _read(filepath_or_buffer, kwds)
    249         return parser
    250 
--> 251     return parser.read()
    252 
    253 _parser_defaults = {

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in read(self, nrows)
    708                 raise ValueError('skip_footer not supported for iteration')
    709 
--> 710         ret = self._engine.read(nrows)
    711 
    712         if self.options.get('as_recarray'):

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in read(self, nrows)
   1210 
   1211             names, data = self._do_date_conversions(names, data)
-> 1212             index, names = self._make_index(data, alldata, names)
   1213 
   1214         # maybe create a mi on the columns

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in _make_index(self, data, alldata, columns, indexnamerow)
    876         elif not self._has_complex_date_col:
    877             index = self._get_simple_index(alldata, columns)
--> 878             index = self._agg_index(index)
    879 
    880         elif self._has_complex_date_col:

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in _agg_index(self, index, try_parse_dates)
    957 
    958             if (try_parse_dates and self._should_parse_dates(i)):
--> 959                 arr = self._date_conv(arr)
    960 
    961             col_na_values = self.na_values

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\parsers.pyc in converter(*date_cols)
   2048                                                dayfirst=dayfirst)
   2049                 except Exception:
-> 2050                     return generic_parser(date_parser, *date_cols)
   2051 
   2052     return converter

C:\WinPython\python-2.7.9\lib\site-packages\pandas\io\date_converters.pyc in generic_parser(parse_func, *cols)
     36     for i in range(N):
     37         args = [c[i] for c in cols]
---> 38         results[i] = parse_func(*args)
     39 
     40     return results

<ipython-input-1-4ac37d43a03f> in <lambda>(ts)
     19                  parse_dates=True,
     20                  date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
---> 21                                                        errors='coerce'),
     22                  header=1,
     23                  skiprows=[2,3],

TypeError: to_datetime() got multiple values for keyword argument 'errors'
```

```
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.9.final.0
python-bits: 32
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 23 Stepping 10, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.15.2
nose: 1.3.4
Cython: 0.21.1
numpy: 1.8.2
scipy: 0.14.0
statsmodels: 0.6.1
IPython: 2.3.1
sphinx: 1.2.3
patsy: 0.3.0
dateutil: 2.3
pytz: 2014.10
bottleneck: None
tables: 3.1.1
numexpr: 2.4
matplotlib: 1.4.2
openpyxl: None
xlrd: 0.9.3
xlwt: None
xlsxwriter: 0.6.4
lxml: 3.4.1
bs4: 4.3.2
html5lib: None
httplib2: None
apiclient: None
rpy2: 2.5.2
sqlalchemy: 0.9.8
pymysql: None
psycopg2: None
```
#### Machine 3

Different physical hardware, same test snippet and same environment (Anaconda3-4.1.0-Windows-x86_64)... 

...produced the same traceback.
#### The Hang-Up

I would have just ignored the deprecation warning and continued to use `coerce=True`, except now I can't get back into a working state...

Reverting to `coerce=True` does not halt the "multiple values for argument 'errors' traceback:

```
import pandas as pd
try:
    from StringIO import StringIO
except ImportError:
    from io import StringIO

fakefile = """\
"TOA5","indoorair(1.2.3)","CR1000","47257","CR1000.Std.28.02","CPU:indoorair.cr1","37538","tsdata"
"TIMESTAMP","RECORD","dc1100_pm_small","dc1100_pm_large","li840a_CO2","li840a_H2O","li840a_cell_T","li840a_cell_P","li840a_dew_T","li840a_pwr_src","typeK_amb_T","logger_panel_T"
"TS","RN","counts/m^3","counts/m^3","ppmv","ppthv","degC","mbar","degC","Vdc","degC","degC"
"","","Smp","Smp","Avg","Avg","Avg","Avg","Avg","Avg","Avg","Avg"
"2016-04-06 13:20:00",5756,1373740,42377,1149.936,10.30014,51.20879,928.455,6.267447,24.1189,21.4,25.93
"2016-04-06 13:21:00",5757,1437306,56503,1147.533,10.30781,51.20538,928.4556,6.278251,24.1182,21.43,25.94
"2016-04-06 13:22:00",5758,1454964,49440,1146.63,10.31073,51.20726,928.449,6.282249,24.11856,21.43,25.95
"2016-04-06 13:23:00",5759,1433775,52972,1145.948,10.30542,51.2077,928.4606,6.274971,24.11839,21.4,25.94
"2016-04-06 13:24:00",5760,1483216,56503,1145.541,10.30182,51.20682,928.451,6.26975,24.11856,21.4,25.95"""

df = pd.read_csv(StringIO(fakefile),
                 index_col=0,
                 parse_dates=True,
                 date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
                                                       coerce=True),
                 header=1,
                 skiprows=[2,3],
                 na_values=['NAN', -7999, 7999],
                 keep_default_na=False)
```

 produces

```
K:\temp.py:24: FutureWarning: the coerce=True keyword is deprecated, use errors='coerce' instead
  coerce=True),
Traceback (most recent call last):
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 2276, in converter
    date_parser(*date_cols), errors='ignore')
  File "K:\temp.py", line 24, in <lambda>
    coerce=True),
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
TypeError: to_datetime() got multiple values for argument 'errors'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 2285, in converter
    dayfirst=dayfirst),
  File "pandas\src\inference.pyx", line 841, in pandas.lib.try_parse_dates (pandas\lib.c:57884)
  File "pandas\src\inference.pyx", line 838, in pandas.lib.try_parse_dates (pandas\lib.c:57802)
  File "K:\temp.py", line 24, in <lambda>
    coerce=True),
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
TypeError: to_datetime() got multiple values for argument 'errors'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "K:\temp.py", line 28, in <module>
    keep_default_na=False)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 562, in parser_f
    return _read(filepath_or_buffer, kwds)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 325, in _read
    return parser.read()
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 815, in read
    ret = self._engine.read(nrows)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 1387, in read
    index, names = self._make_index(data, alldata, names)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 1030, in _make_index
    index = self._agg_index(index)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 1111, in _agg_index
    arr = self._date_conv(arr)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 2288, in converter
    return generic_parser(date_parser, *date_cols)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\date_converters.py", line 38, in generic_parser
    results[i] = parse_func(*args)
  File "K:\temp.py", line 24, in <lambda>
    coerce=True),
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
TypeError: to_datetime() got multiple values for argument 'errors'
```

Neither does removing _both_ `coerce` and `errors` arguments:

```
import pandas as pd
try:
    from StringIO import StringIO
except ImportError:
    from io import StringIO

fakefile = """\
"TOA5","indoorair(1.2.3)","CR1000","47257","CR1000.Std.28.02","CPU:indoorair.cr1","37538","tsdata"
"TIMESTAMP","RECORD","dc1100_pm_small","dc1100_pm_large","li840a_CO2","li840a_H2O","li840a_cell_T","li840a_cell_P","li840a_dew_T","li840a_pwr_src","typeK_amb_T","logger_panel_T"
"TS","RN","counts/m^3","counts/m^3","ppmv","ppthv","degC","mbar","degC","Vdc","degC","degC"
"","","Smp","Smp","Avg","Avg","Avg","Avg","Avg","Avg","Avg","Avg"
"2016-04-06 13:20:00",5756,1373740,42377,1149.936,10.30014,51.20879,928.455,6.267447,24.1189,21.4,25.93
"2016-04-06 13:21:00",5757,1437306,56503,1147.533,10.30781,51.20538,928.4556,6.278251,24.1182,21.43,25.94
"2016-04-06 13:22:00",5758,1454964,49440,1146.63,10.31073,51.20726,928.449,6.282249,24.11856,21.43,25.95
"2016-04-06 13:23:00",5759,1433775,52972,1145.948,10.30542,51.2077,928.4606,6.274971,24.11839,21.4,25.94
"2016-04-06 13:24:00",5760,1483216,56503,1145.541,10.30182,51.20682,928.451,6.26975,24.11856,21.4,25.95"""

df = pd.read_csv(StringIO(fakefile),
                 index_col=0,
                 parse_dates=True,
                 date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S'),
                                                       #errors='coerce'),
                 header=1,
                 skiprows=[2,3],
                 na_values=['NAN', -7999, 7999],
                 keep_default_na=False)
```

produces

```
Traceback (most recent call last):
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 2276, in converter
    date_parser(*date_cols), errors='ignore')
  File "K:\temp.py", line 23, in <lambda>
    date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S'),
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 291, in to_datetime
    unit=unit, infer_datetime_format=infer_datetime_format)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 427, in _to_datetime
    return _convert_listlike(arg, box, format)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 398, in _convert_listlike
    require_iso8601=require_iso8601
  File "pandas\tslib.pyx", line 2134, in pandas.tslib.array_to_datetime (pandas\tslib.c:41972)
  File "pandas\tslib.pyx", line 2150, in pandas.tslib.array_to_datetime (pandas\tslib.c:38535)
AssertionError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 2285, in converter
    dayfirst=dayfirst),
  File "pandas\src\inference.pyx", line 841, in pandas.lib.try_parse_dates (pandas\lib.c:57884)
  File "pandas\src\inference.pyx", line 838, in pandas.lib.try_parse_dates (pandas\lib.c:57802)
  File "K:\temp.py", line 23, in <lambda>
    date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S'),
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 291, in to_datetime
    unit=unit, infer_datetime_format=infer_datetime_format)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 429, in _to_datetime
    return _convert_listlike(np.array([arg]), box, format)[0]
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 398, in _convert_listlike
    require_iso8601=require_iso8601
  File "pandas\tslib.pyx", line 2134, in pandas.tslib.array_to_datetime (pandas\tslib.c:41972)
  File "pandas\tslib.pyx", line 2150, in pandas.tslib.array_to_datetime (pandas\tslib.c:38535)
AssertionError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "K:\temp.py", line 28, in <module>
    keep_default_na=False)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 562, in parser_f
    return _read(filepath_or_buffer, kwds)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 325, in _read
    return parser.read()
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 815, in read
    ret = self._engine.read(nrows)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 1387, in read
    index, names = self._make_index(data, alldata, names)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 1030, in _make_index
    index = self._agg_index(index)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 1111, in _agg_index
    arr = self._date_conv(arr)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\parsers.py", line 2288, in converter
    return generic_parser(date_parser, *date_cols)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\io\date_converters.py", line 38, in generic_parser
    results[i] = parse_func(*args)
  File "K:\temp.py", line 23, in <lambda>
    date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S'),
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\util\decorators.py", line 91, in wrapper
    return func(*args, **kwargs)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 291, in to_datetime
    unit=unit, infer_datetime_format=infer_datetime_format)
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 429, in _to_datetime
    return _convert_listlike(np.array([arg]), box, format)[0]
  File "C:\Users\pokeeffe\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\tseries\tools.py", line 398, in _convert_listlike
    require_iso8601=require_iso8601
  File "pandas\tslib.pyx", line 2134, in pandas.tslib.array_to_datetime (pandas\tslib.c:41972)
  File "pandas\tslib.pyx", line 2150, in pandas.tslib.array_to_datetime (pandas\tslib.c:38535)
AssertionError
```

To be clear, I can still use `coerce=True` in older versions of pandas. For example, in 0.15.2, both of these work fine:

```
...

df = pd.read_csv(StringIO(fakefile),
                 index_col=0,
                 parse_dates=True,
                 date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S',
                                                       coerce=True),
                 header=1,
                 skiprows=[2,3],
                 na_values=['NAN', -7999, 7999],
                 keep_default_na=False)
```

```
...

df = pd.read_csv(StringIO(fakefile),
                 index_col=0,
                 parse_dates=True,
                 date_parser=lambda ts: pd.to_datetime(ts, '%Y-%m-%d %H:%M:%S'),
                 #                                      coerce=True),
                 header=1,
                 skiprows=[2,3],
                 na_values=['NAN', -7999, 7999],
                 keep_default_na=False)
```

---

_Whew! I know that was a lot of scrolling sorry_
