Error while processing list of dictionarie in cassandra through pyspark

I have below code which I am trying to execute:

prepared_statement = session.prepare("update table set somecol = ? where col = ?")
params = ([Row('key1': value1), Row('ke2': value2), .., Row('keyn': valuen)], value2)
batch.add(prepared_statement, params)

But code is failing while adding statement in batch. Below is the error which I am receiving. can someone pls help with this?

  File "/mnt/yarn/<path>/pyspark.zip/pyspark/worker.py", line 619, in main
    process()
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/worker.py", line 609, in process
    out_iter = func(split_index, iterator)
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/rdd.py", line 2918, in pipeline_func
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/rdd.py", line 2918, in pipeline_func
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/rdd.py", line 2918, in pipeline_func
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/rdd.py", line 417, in func
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/rdd.py", line 933, in func
  File "/mnt/yarn/<path>/processor/python_file.py", line 35, in <lambda>
  File "/mnt/yarn/<path>/processor/python_file.py", line 111, in partition_method
    raise e
  File "/mnt/yarn/<path>/processor/python_file.py", line 103, in partition_method
    raise e
  File "/mnt/yarn/<path>/processor/python_file.py", line 72, in partition_method
    batch_statement.add(prepared_statement, params)
  File "cassandra/query.py", line 825, in cassandra.query.BatchStatement.add
  File "cassandra/query.py", line 504, in cassandra.query.PreparedStatement.bind
  File "cassandra/query.py", line 634, in cassandra.query.BoundStatement.bind
  File "cassandra/cqltypes.py", line 808, in cassandra.cqltypes._ParameterizedType.serialize
  File "cassandra/cqltypes.py", line 847, in cassandra.cqltypes._SimpleParameterizedType.serialize_safe
  File "cassandra/cqltypes.py", line 313, in cassandra.cqltypes._CassandraType.to_binary
  File "cassandra/cqltypes.py", line 808, in cassandra.cqltypes._ParameterizedType.serialize
  File "cassandra/cqltypes.py", line 1034, in cassandra.cqltypes.UserType.serialize_safe
  File "/mnt/yarn/<path>/pyspark.zip/pyspark/sql/types.py", line 1556, in __getitem__
    return super(Row, self).__getitem__(item)
IndexError: tuple index out of range