Problem description: PyTorch Lightning error: KeyError: ‘hidden_ states’.

model = BertModel.from_pretrained('bert-base-uncased')

Solution: add a parameter after the above code, config=BertConfig.from_pretrained(‘bert-base-uncased’,output_hidden_states=True), as below:

model = BertModel.from_pretrained('bert-base-uncased', config=BertConfig.from_pretrained('bert-base-uncased',output_hidden_states=True))