preprocessing error

ERROR DESCRIPTION:

Error using cellstr (line 49)
Conversion to cellstr from double is not possible.
Error in conn_datasetcopy (line 44)
existf=conn_existfile(cellstr(f1));
Error in conn_setup_preproc (line 2727)
conn_datasetcopy(sets,'original data',subjects);
Error in conn (line 1081)
ok=conn_setup_preproc('',varargin{2:end});
Error in conn_menumanager (line 120)
feval(CONN_MM.MENU{n0}.callback{n1}{1},CONN_MM.MENU{n0}.callback{n1}{2:end});
CONN18.b
SPM12 + DEM FieldMap MEEGtools
Matlab v.2017b
project: CONN18.b
storage: 437.8Gb available