title: Pandas Dataframe Error 'StringArray requires a sequence of strings or pandas.NA'
body: <p>I've been reading from an excel sheet for the past month with no problems using Pandas.</p>
  
  <p>Recently though I made a change to my date formats (which have now been switched back to their original formats mm/dd/yyyy).</p>
  
  <p>All of sudden Pandas throws an error now when I try to read my .xlsm</p>
  
  <p>Below is the full error</p>
  
  <pre><code>---------------------------------------------------------------------------
  ValueError                                Traceback (most recent call last)
  &lt;ipython-input-5-655581a0eaab&gt; in &lt;module&gt;
  ----&gt; 1 inv = p.read(r'C:\Users\Jake\OneDrive\Documents\Eastern\Inventory\Inventory_Log.xlsm')
  
  ~\Anaconda3\lib\site-packages\pyinv\__init__.py in read(filepath)
       36     'Cert_Expire':'string',
       37     'Rating':'string',
  ---&gt; 38     'Notes':'string'
       39     })
       40     amount = inv.Item.count()
  
  ~\Anaconda3\lib\site-packages\pandas\io\excel\_base.py in read_excel(io, sheet_name, header, names, index_col, usecols, squeeze, dtype, engine, converters, true_values, false_values, skiprows, nrows, na_values, keep_default_na, verbose, parse_dates, date_parser, thousands, comment, skipfooter, convert_float, mangle_dupe_cols, **kwds)
      332         convert_float=convert_float,
      333         mangle_dupe_cols=mangle_dupe_cols,
  --&gt; 334         **kwds,
      335     )
      336 
  
  ~\Anaconda3\lib\site-packages\pandas\io\excel\_base.py in parse(self, sheet_name, header, names, index_col, usecols, squeeze, converters, true_values, false_values, skiprows, nrows, na_values, parse_dates, date_parser, thousands, comment, skipfooter, convert_float, mangle_dupe_cols, **kwds)
      883             convert_float=convert_float,
      884             mangle_dupe_cols=mangle_dupe_cols,
  --&gt; 885             **kwds,
      886         )
      887 
  
  ~\Anaconda3\lib\site-packages\pandas\io\excel\_base.py in parse(self, sheet_name, header, names, index_col, usecols, squeeze, dtype, true_values, false_values, skiprows, nrows, na_values, verbose, parse_dates, date_parser, thousands, comment, skipfooter, convert_float, mangle_dupe_cols, **kwds)
      510                 )
      511 
  --&gt; 512                 output[asheetname] = parser.read(nrows=nrows)
      513 
      514                 if not squeeze or isinstance(output[asheetname], DataFrame):
  
  ~\Anaconda3\lib\site-packages\pandas\io\parsers.py in read(self, nrows)
     1131     def read(self, nrows=None):
     1132         nrows = _validate_integer("nrows", nrows)
  -&gt; 1133         ret = self._engine.read(nrows)
     1134 
     1135         # May alter columns / col_dict
  
  ~\Anaconda3\lib\site-packages\pandas\io\parsers.py in read(self, rows)
     2462         columns, data = self._do_date_conversions(columns, data)
     2463 
  -&gt; 2464         data = self._convert_data(data)
     2465         index, columns = self._make_index(data, alldata, columns, indexnamerow)
     2466 
  
  ~\Anaconda3\lib\site-packages\pandas\io\parsers.py in _convert_data(self, data)
     2532             self.verbose,
     2533             clean_conv,
  -&gt; 2534             clean_dtypes,
     2535         )
     2536 
  
  ~\Anaconda3\lib\site-packages\pandas\io\parsers.py in _convert_to_ndarrays(self, dct, na_values, na_fvalues, verbose, converters, dtypes)
     1725                         # invalid input to is_bool_dtype
     1726                         pass
  -&gt; 1727                     cvals = self._cast_types(cvals, cast_type, c)
     1728 
     1729             result[c] = cvals
  
  ~\Anaconda3\lib\site-packages\pandas\io\parsers.py in _cast_types(self, values, cast_type, column)
     1823             array_type = cast_type.construct_array_type()
     1824             try:
  -&gt; 1825                 return array_type._from_sequence_of_strings(values, dtype=cast_type)
     1826             except NotImplementedError:
     1827                 raise NotImplementedError(
  
  ~\Anaconda3\lib\site-packages\pandas\core\arrays\string_.py in _from_sequence_of_strings(cls, strings, dtype, copy)
      199     @classmethod
      200     def _from_sequence_of_strings(cls, strings, dtype=None, copy=False):
  --&gt; 201         return cls._from_sequence(strings, dtype=dtype, copy=copy)
      202 
      203     def __arrow_array__(self, type=None):
  
  ~\Anaconda3\lib\site-packages\pandas\core\arrays\string_.py in _from_sequence(cls, scalars, dtype, copy)
      195             result[na_values] = StringDtype.na_value
      196 
  --&gt; 197         return cls(result)
      198 
      199     @classmethod
  
  ~\Anaconda3\lib\site-packages\pandas\core\arrays\string_.py in __init__(self, values, copy)
      164         self._dtype = StringDtype()
      165         if not skip_validation:
  --&gt; 166             self._validate()
      167 
      168     def _validate(self):
  
  ~\Anaconda3\lib\site-packages\pandas\core\arrays\string_.py in _validate(self)
      169         """Validate that we only store NA or strings."""
      170         if len(self._ndarray) and not lib.is_string_array(self._ndarray, skipna=True):
  --&gt; 171             raise ValueError("StringArray requires a sequence of strings or pandas.NA")
      172         if self._ndarray.dtype != "object":
      173             raise ValueError(
  
  ValueError: StringArray requires a sequence of strings or pandas.NA
  </code></pre>
  
  <p>This is happening because when pandas is reading it I'm having it convert the columns to string dtypes. No idea why the date formats broke this.</p>
  
  <p>Currently using Pandas 1.0.1</p>
  
  <p>Any information is greatly appreciated.</p>
  
  <p>I will provide more details if needed.</p>