SNS Client Tuple error

[SagarK-TI]

response = sns_client.publish(TargetArn=sns_arn,Message=json.dumps({'default': json.dumps({"foo":"bar"})}),MessageGroupId= 'FIG',MessageStructure='json')

I'm getting this error Exception in /test-api: 'tuple' object has no attribute 'split'.
I have checked all the data types of the object being passed in .publish() method and all of them are str or dict which is being converted to str

Has anyone come across same one?

Here is how I initialise the boto3 client it:
def get_sns_client(): session = boto3.Session( aws_access_key_id=aws_access_key_id, aws_secret_access_key=aws_secret_access_key, aws_session_token=aws_session_token, region_name='us-east-1') sns_client=session.client('sns', region_name='us-east-1') return sns_client