[FIXED] Error in Tensorflow 2.5.0 while using Colab TPU - NotFoundError: Could not find metadata file. [Op.DatasetCardinality]

Issue

Note: These same steps work without any errors on Colab GPU.

Please help me with this. I created a dataset and saved it as file

data = tf.data.Dataset.from_tensor_slices(( features, labels))
tf.data.experimental.save(data, myfile)

When I try to load it

data = tf.data.experimental.load(myfile)

and run any function on the data like len(data), data.batch(16) or data.take(1) then I get this error:

NotFoundError: Could not find metadata file. [Op:DatasetCardinality]

TPU config

resolver = tf.distribute.cluster_resolver.TPUClusterResolver(tpu='')
tf.config.experimental_connect_to_cluster(resolver)
# This is the TPU initialization code that has to be at the beginning.
tf.tpu.experimental.initialize_tpu_system(resolver)

Is it similar to this TF1.14][TPU]Can not use custom TFrecord dataset on Colab using TPU ?

Solution

After some more debugging I got this error:

UnimplementedError: File system scheme '[local]' not implemented (file: './data/temp/2692738424590406024')
    Encountered when executing an operation using EagerExecutor. This error cancels all future operations and poisons their output tensors. [Op:DatasetCardinality]

I found this explanation:

Cloud TPUs can only access data in GCS as only the GCS file system is registered.

More info here: File system scheme '[local]' not implemented in Google Colab TPU

Answered By - Nikhil