Hi, sorry for the late answer. I tried to convert it with this command
python ~/Work/transformers/src/transformers/convert_mbart_original_checkpoint_to_pytorch.py --hf_config facebook/mbart-large-cc25 wmt14-en-de/checkpoint_best.pt out

but I get following error message:
    Traceback (most recent call last):
      File "../../transformers/src/transformers/convert_mbart_original_checkpoint_to_pytorch.py", line 36, in <module>
        model = convert_fairseq_mbart_checkpoint_from_disk(args.fairseq_path, hf_config_path=args.hf_config)
      File "../../transformers/src/transformers/convert_mbart_original_checkpoint_to_pytorch.py", line 18, in convert_fairseq_mbart_checkpoint_from_disk
        model.model.load_state_dict(state_dict)
      File "/home/wirawan/miniconda3/envs/transformers-cuda9/lib/python3.7/site-packages/torch/nn/modules/module.py", line 847, in load_state_dict
        self.__class__.__name__, "\n\t".join(error_msgs)))
    RuntimeError: Error(s) in loading state_dict for BartModel:
            Unexpected key(s) in state_dict: "decoder.output_projection.weight".

However it did work to convert the original mbart-finetuned_en-ro model from facebook https://dl.fbaipublicfiles.com/fairseq/models/mbart/mbart.cc25.ft.enro.tar.gz 1
There was a bug report with the same error message https://github.com/pytorch/fairseq/issues/2031 17 , but I can’t make the solution/work around to work.