simpletransformers: size mismatch for classifier.weight and classifier.bias even after providing correct arguments with simpletransformers library

Question

I'm using simpletransformers library for fine-tuning a BERT model for Named Entity Recognition (NER) on a custom dataset which is having 13 distinct entities. Even after providing model_args.labels_list, the NERModel() produce the following error.

RuntimeError: Error(s) in loading state_dict for BertForTokenClassification:
    size mismatch for classifier.weight: copying a param with shape torch.Size([9, 768]) from checkpoint, the shape in current model is torch.Size([13, 768]).
    size mismatch for classifier.bias: copying a param with shape torch.Size([9]) from checkpoint, the shape in current model is torch.Size([13]).

Sample code:

from simpletransformers.ner import NERModel, NERArgs

model_args = NERArgs()
model_args.labels_list = ["ENT1", "ENT2", "ENT3", "ENT4", "ENT5", "ENT6", "ENT7", "ENT8", "ENT9", "ENT10", "ENT11", "ENT12", "ENT13"]  # this list is having thirteen entities from my dataset

model = NERModel(
    "bert",
    "dslim/bert-base-NER",
    args=model_args,
)

Answer 1

I had the same problem. I updated my simpletransformers and it solved the problem.