Increasing Replication Factor in Kafka gives error - "There is an existing assignment running"

I am trying to increase the replication factor of a topic in Apache Kafka.In order to do so I am using the command

kafka-reassign-partitions --zookeeper ${zookeeperid} --reassignment-json-file ${aFile} --execute

Initially my topic has a replication factor of 1 and has 5 partitions, I am trying to increase it's replication factor to 3.There are quite a bit of messages in my topic. When I run the above command the error is - "There is an existing assignment running". My json file looks like this :

{
    "version": 1,
    "partitions": [
        {
            "topic": "IncreaseReplicationTopic",
            "partition": 0,
            "replicas": [2,4,0]
        },{
            "topic": "IncreaseReplicationTopic",
            "partition": 1,
            "replicas": [3,2,1]
        }, {
            "topic": "IncreaseReplicationTopic",
            "partition": 2,
            "replicas": [4,1,0]
        }, {
            "topic": "IncreaseReplicationTopic",
            "partition": 3,
            "replicas": [0,1,3]
        }, {
            "topic": "IncreaseReplicationTopic",
            "partition": 4,
            "replicas": [1,4,2]
        }
    ]
}

I am not able to figure out where I am getting wrong. Any pointers will be greatly appreciated.