Error reading EEGLAB file (buffer too small)

This issue was reported in our forum using this example file.

raw = mne.io.read_raw_eeglab("EC_CON1.set")
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-90625f7fcaf5> in <module>
----> 1 raw = mne.io.read_raw_eeglab("EC_CON1.set")

/usr/local/lib/python3.9/site-packages/mne/io/eeglab/eeglab.py in read_raw_eeglab(input_fname, eog, preload, uint16_codec, verbose)
    217     .. versionadded:: 0.11.0
    218     """
--> 219     return RawEEGLAB(input_fname=input_fname, preload=preload,
    220                      eog=eog, verbose=verbose, uint16_codec=uint16_codec)
    221 

<decorator-gen-261> in __init__(self, input_fname, eog, preload, uint16_codec, verbose)

/usr/local/lib/python3.9/site-packages/mne/io/eeglab/eeglab.py in __init__(self, input_fname, eog, preload, uint16_codec, verbose)
    316                  preload=False, uint16_codec=None, verbose=None):  # noqa: D102
    317         input_fname = _check_fname(input_fname, 'read', True, 'input_fname')
--> 318         eeg = _check_load_mat(input_fname, uint16_codec)
    319         if eeg.trials != 1:
    320             raise TypeError('The number of trials is %d. It must be 1 for raw'

/usr/local/lib/python3.9/site-packages/mne/io/eeglab/eeglab.py in _check_load_mat(fname, uint16_codec)
     57     """Check if the mat struct contains 'EEG'."""
     58     from ...externals.pymatreader import read_mat
---> 59     eeg = read_mat(fname, uint16_codec=uint16_codec)
     60     if 'ALLEEG' in eeg:
     61         raise NotImplementedError(

/usr/local/lib/python3.9/site-packages/mne/externals/pymatreader/pymatreader.py in read_mat(filename, variable_names, ignore_fields, uint16_codec)
     87                 extra_kwargs['uint16_codec'] = uint16_codec
     88 
---> 89             raw_data = scipy.io.loadmat(fid, struct_as_record=True,
     90                                         squeeze_me=True, mat_dtype=False,
     91                                         variable_names=variable_names,

/usr/local/lib/python3.9/site-packages/scipy/io/matlab/mio.py in loadmat(file_name, mdict, appendmat, **kwargs)
    224     with _open_file_context(file_name, appendmat) as f:
    225         MR, _ = mat_reader_factory(f, **kwargs)
--> 226         matfile_dict = MR.get_variables(variable_names)
    227 
    228     if mdict is not None:

/usr/local/lib/python3.9/site-packages/scipy/io/matlab/mio5.py in get_variables(self, variable_names)
    330                 continue
    331             try:
--> 332                 res = self.read_var_array(hdr, process)
    333             except MatReadError as err:
    334                 warnings.warn(

/usr/local/lib/python3.9/site-packages/scipy/io/matlab/mio5.py in read_var_array(self, header, process)
    290            `process`.
    291         '''
--> 292         return self._matrix_reader.array_from_header(header, process)
    293 
    294     def get_variables(self, variable_names=None):

mio5_utils.pyx in scipy.io.matlab.mio5_utils.VarReader5.array_from_header()

mio5_utils.pyx in scipy.io.matlab.mio5_utils.VarReader5.array_from_header()

mio5_utils.pyx in scipy.io.matlab.mio5_utils.VarReader5.read_struct()

mio5_utils.pyx in scipy.io.matlab.mio5_utils.VarReader5.read_mi_matrix()

mio5_utils.pyx in scipy.io.matlab.mio5_utils.VarReader5.array_from_header()

mio5_utils.pyx in scipy.io.matlab.mio5_utils.VarReader5.read_char()

TypeError: buffer is too small for requested array

It looks like this is related to reading the .mat file.

[drammock]

https://github.com/mne-tools/mne-python/issues/8226#issuecomment-965439900

[mmagnuski]

Quoting the docs for the uint16_codec parameter of read_raw_eeglab:

uint16_codec : str | None
    If your \*.set file contains non-ascii characters, sometimes reading
    it may fail and give rise to error message stating that "buffer is
    too small". ``uint16_codec`` allows to specify what codec (for example:
    'latin1' or 'utf-8') should be used when reading character arrays and
    can therefore help you solve this problem.