title: AttributeError: 'GPT2TokenizerFast' object has no attribute 'max_len'
body: <p>I am just using the huggingface transformer library and get the following message when running run_lm_finetuning.py: AttributeError: 'GPT2TokenizerFast' object has no attribute 'max_len'. Anyone else with this problem or an idea how to fix it? Thanks!</p>
  <p>My full experiment run:
  mkdir experiments</p>
  <p>for epoch in 5
  do
  python run_lm_finetuning.py <br />
  --model_name_or_path distilgpt2 <br />
  --model_type gpt2 <br />
  --train_data_file small_dataset_train_preprocessed.txt <br />
  --output_dir experiments/epochs_$epoch <br />
  --do_train <br />
  --overwrite_output_dir <br />
  --per_device_train_batch_size 4 <br />
  --num_train_epochs $epoch
  done</p>