Adding Overlay for given bit file is not working 'NoneType' object has no attribute 'split' Error in

Pynq image - 2.7
Board - Pynq-Z2
hwh file :
design_1.hwh (332.2 KB)

design_1_wrapper.bit (3.9 MB)

I am loading this bitfile and the hwh file and then I cannot load the overlay. I am getting error ‘NoneType’ object has no attribute ‘split’

This is the block design of softcore linked zynq