Ner_run.py: ValueError: Can't find a valid checkpoint

I want to start my train process from the last checkpoint

!python ./transformers/examples/token-classification/run_ner.py \

    --model_name_or_path xlm-roberta-base \

    --output_dir /content/drive/MyDrive/model/roberta \

    --do_train \

    --test_file /content/nertest.json \

    --validation_file /content/nerval.json \

    --train_file /content/nertrain.json \

    --num_train_epochs 4.0

But I get this error:

ValueError: Can't find a valid checkpoint at /content/drive/MyDrive/model/roberta/checkpoint-4500

And this is my checkpoint-4500 folder

So, what is the reason of it? What is valid checkpoint?

Problem have been solved