Hi there, need your help!
I was using some older transformers code and it was working fine for last 2 month until suddenly it started giving this error in a place that never changed:
AssertionError                            Traceback (most recent call last)
<ipython-input-31-c365f437b895> in <module>()
      9 tokenizer = tokenizer_class.from_pretrained(args['model_name'])
     10 
---> 11 model = model_class.from_pretrained(args['model_name'])
     12 model.to(device);
     13 

3 frames
/usr/local/lib/python3.6/dist-packages/pytorch_transformers/modeling_utils.py in from_pretrained(cls, pretrained_model_name_or_path, *model_args, **kwargs)
    534 
    535         # Instantiate model.
--> 536         model = cls(config, *model_args, **model_kwargs)
    537 
    538         if state_dict is None and not from_tf:

/usr/local/lib/python3.6/dist-packages/pytorch_transformers/modeling_xlm.py in __init__(self, config)
    842         self.num_labels = config.num_labels
    843 
--> 844         self.transformer = XLMModel(config)
    845         self.sequence_summary = SequenceSummary(config)
    846 

/usr/local/lib/python3.6/dist-packages/pytorch_transformers/modeling_xlm.py in __init__(self, config)
    543         if config.n_langs > 1 and config.use_lang_emb:
    544             self.lang_embeddings = nn.Embedding(self.n_langs, self.dim)
--> 545         self.embeddings = nn.Embedding(self.n_words, self.dim, padding_idx=self.pad_index)
    546         self.layer_norm_emb = nn.LayerNorm(self.dim, eps=config.layer_norm_eps)
    547 

/usr/local/lib/python3.6/dist-packages/torch/nn/modules/sparse.py in __init__(self, num_embeddings, embedding_dim, padding_idx, max_norm, norm_type, scale_grad_by_freq, sparse, _weight)
     86         if padding_idx is not None:
     87             if padding_idx > 0:
---> 88                 assert padding_idx < self.num_embeddings, 'Padding_idx must be within num_embeddings'
     89             elif padding_idx < 0:
     90                 assert padding_idx >= -self.num_embeddings, 'Padding_idx must be within num_embeddings'

AssertionError: Padding_idx must be within num_embeddings