Tensorflow error when loading checkpoints

[Sal2040]

I am trying to rebuild the model using tf.official like so:

import tensorflow as tf
import official
import json

config_dict = json.loads(tf.io.gfile.GFile('/content/drive/MyDrive/TREC-COVID/scibert_scivocab_uncased/bert_config.json').read())

bert_config = official.nlp.bert.configs.BertConfig.from_dict(config_dict)
bert_model = official.nlp.bert.bert_models.get_transformer_encoder(bert_config)

checkpoint = tf.train.Checkpoint(encoder=bert_model)
checkpoint.read('/content/drive/MyDrive/TREC-COVID/scibert_scivocab_uncased/bert_model.ckpt').assert_consumed()

The last line of the code runs into an error:

AssertionError                            Traceback (most recent call last)
<ipython-input-65-2c94af81d21f> in <module>()
      1 checkpoint = tf.train.Checkpoint(encoder=bert_model)
----> 2 checkpoint.read('/content/drive/MyDrive/TREC-COVID/scibert_scivocab_uncased/bert_model.ckpt').assert_consumed()

/usr/local/lib/python3.7/dist-packages/tensorflow/python/training/tracking/util.py in assert_consumed(self)
   1000       raise AssertionError(
   1001           "Some objects had attributes which were not restored:{}".format(
-> 1002               "".join(unused_attribute_strings)))
   1003     for trackable in self._graph_view.list_objects():
   1004       # pylint: disable=protected-access

AssertionError: Some objects had attributes which were not restored:
    <tf.Variable 'word_embeddings/embeddings:0' shape=(31090, 768) dtype=float32, numpy=
array([[ 0.02573318, -0.00267772,  0.01776482, ..., -0.02813556,
        -0.0021598 , -0.02582178],
       [ 0.00280955, -0.01805187,  0.03772264, ...,  0.02741825,
         0.00221546,  0.01261247],
       [ 0.00038168,  0.00612852, -0.02045917, ...,  0.00615935,
        -0.01438048, -0.00059851],
       ...,

Could you please advise where the problem might be?

Thanks.