mBART 50 models not found in model shortcut name list
Transformers version: 4.4.0.dev0

Hello, I'm trying to fine-tune mBART 50 with your seq2seq examples.

Getting this error:

Model name 'facebook/mbart-large-50' not found in model shortcut name list (facebook/mbart-large-en-ro, facebook/mbart-large-cc25).

Traceback (most recent call last):
  File "/content/transformers/examples/seq2seq/run_seq2seq.py", line 668, in <module>
    main()
  File "/content/transformers/examples/seq2seq/run_seq2seq.py", line 349, in main
    use_auth_token=True if model_args.use_auth_token else None,
  File "/usr/local/lib/python3.6/dist-packages/transformers/models/auto/tokenization_auto.py", line 399, in from_pretrained
    return tokenizer_class_fast.from_pretrained(pretrained_model_name_or_path, *inputs, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/transformers/tokenization_utils_base.py", line 1789, in from_pretrained
    resolved_vocab_files, pretrained_model_name_or_path, init_configuration, *init_inputs, **kwargs
  File "/usr/local/lib/python3.6/dist-packages/transformers/tokenization_utils_base.py", line 1806, in _from_pretrained
    **(copy.deepcopy(kwargs)),
  File "/usr/local/lib/python3.6/dist-packages/transformers/tokenization_utils_base.py", line 1860, in _from_pretrained
    tokenizer = cls(*init_inputs, **init_kwargs)
  File "/usr/local/lib/python3.6/dist-packages/transformers/models/mbart/tokenization_mbart.py", line 109, in __init__
    self.set_src_lang_special_tokens(kwargs.get("src_lang", "en_XX"))
  File "/usr/local/lib/python3.6/dist-packages/transformers/models/mbart/tokenization_mbart.py", line 199, in set_src_lang_special_tokens
    self.cur_lang_code = self.lang_code_to_id[src_lang]
KeyError: None

Any Ideas on how to fix this?

Thanks
Hi @codingnoobneedshelp , thank for reporting this issue. Right now MBart50Tokenizer does not work with `AutoTokenizer`.
There will be a new script for translation in the next ~2 weeks that will handle this issue. For now, you could just modify the script to  use `MBart50Tokenizer`, instead of `AutoTokenizer`.<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.<|||||>Hi @codingnoobneedshelp 

This is now resolved, the `run_translation.py` script now supports fine-tuning mBART-50.