how to modify multigpu_train.py to train on cpu with custom dataset

[vidkr]

how to modify multigpu_train.py to train on cpu with custom dataset. I create a dataset of my own , but getting error while trying to run multigpu_train.py. i attached a file with this where you can see error and warning gererated while running multi_gpu training. Help me to solve these errors
model_issue_output.pdf