TypeError: Signature mismatch. Keys must be dtype <dtype: 'string'>, got <dtype:'int64'>
<p>While running the <a href="https://github.com/tensorflow/tensorflow/blob/master/tensorflow/examples/learn/wide_n_deep_tutorial.py" rel="nofollow noreferrer">wide_n_deep_tutorial</a> program from TensorFlow on my dataset, the following error is displayed.</p>

<pre><code>"TypeError: Signature mismatch. Keys must be dtype &lt;dtype: 'string'&gt;, got &lt;dtype:'int64'&gt;"
</code></pre>

<p><img src="https://i.stack.imgur.com/aqs3x.png" alt="enter image description here"></p>

<p>Following is the code snippet:</p>

<pre><code> def input_fn(df):
  """Input builder function."""
  # Creates a dictionary mapping from each continuous feature column name (k) to
  # the values of that column stored in a constant Tensor.
  continuous_cols = {k: tf.constant(df[k].values) for k in CONTINUOUS_COLUMNS}
  # Creates a dictionary mapping from each categorical feature column name (k)
  # to the values of that column stored in a tf.SparseTensor.
  categorical_cols = {k: tf.SparseTensor(
      indices=[[i, 0] for i in range(df[k].size)],
      values=df[k].values,
      shape=[df[k].size, 1])
                      for k in CATEGORICAL_COLUMNS}

  # Merges the two dictionaries into one.
  feature_cols = dict(continuous_cols)
  feature_cols.update(categorical_cols)
  # Converts the label column into a constant Tensor.
  label = tf.constant(df[LABEL_COLUMN].values)
  # Returns the feature columns and the label.

  return feature_cols, label



def train_and_eval():
  """Train and evaluate the model."""
  train_file_name, test_file_name = maybe_download()

  df_train=train_file_name
  df_test=test_file_name

  df_train[LABEL_COLUMN] = (
      df_train["impression_flag"].apply(lambda x: "generated" in x)).astype(str)

  df_test[LABEL_COLUMN] = (
      df_test["impression_flag"].apply(lambda x: "generated" in x)).astype(str)

  model_dir = tempfile.mkdtemp() if not FLAGS.model_dir else FLAGS.model_dir
  print("model directory = %s" % model_dir)

  m = build_estimator(model_dir)
  print('model succesfully build!')
  m.fit(input_fn=lambda: input_fn(df_train), steps=FLAGS.train_steps)
  print('model fitted!!')
  results = m.evaluate(input_fn=lambda: input_fn(df_test), steps=1)
  for key in sorted(results):
    print("%s: %s" % (key, results[key]))
</code></pre>

<p>Any help is appreciated.</p>