Help with finetuning mBART on summarization task

Models
1

Hi everyone,
I am trying to finetune mbart-50-large on a summarization task. I am using the run_summarization.py script from transformers repo. But I keep getting this error :

index = int(index) 
int() argument must be a string, a bytes-like object or a number, not 'NoneType'
2

Did you find the solution to this . Even I am getting the same error post pretraining on a mbart model .