AttributeError: 'str' object has no attribute 'extend'

[vas2201]

@scandium:/projects/LigandNMR/test1$ python3 ../DP5-master/PyDP4_GUI.py
/projects/LigandNMR/test1/../DP5-master/PyDP4_GUI.py:8: MatplotlibDeprecationWarning:
The matplotlib.backends.backend_qt4agg backend was deprecated in Matplotlib 3.3 and will be removed two minor releases later.
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
QLayout: Attempting to add QLayout "" to CalculationTab "", which already has a layout
QLayout: Attempting to add QLayout "" to CalculationTab "", which already has a layout
QLayout: Attempting to add QLayout "" to CalculationTab "", which already has a layout
QLayout: Attempting to add QLayout "" to CalculationTab "", which already has a layout
Traceback (most recent call last):
File "/home/nmrbox/spenumutchu/projects/LigandNMR/test1/../DP5-master/PyDP4_GUI.py", line 2600, in runPyDP4
self.NMRData, self.Isomers, self.settings, self.DP4Data,self.DP5Data = PyDP4.main(ui.table_widget.Tab1.settings)
File "/home/nmrbox/spenumutchu/projects/LigandNMR/DP5-master/PyDP4.py", line 203, in main
settings.InputFiles.extend(StructureInput.GenerateSDFFromTxt(settings.Smiles, 'Smiles'))
AttributeError: 'str' object has no attribute 'extend'
Aborted (core dumped)
(DP5) @scandium:/projects/LigandNMR/test1$

[vas2201]

If possible, could you please mention what is sofware /lib versions of python, matplotlib and others
that are compatibale to run PD5 ?