When I set and used Role's policy in python, the following error occurred and I was addicted to it for an hour.

botocore.errorfactory.MalformedPolicyDocumentException: An error occurred (MalformedPolicyDocument) when calling the PutRolePolicy operation: The policy failed legacy parsing

The program used is as follows.

# coding:utf-8
# !/usr/bin/python

import boto3
iamClient = boto3.client('iam')
policy = '''
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "mobileanalytics:PutEvents",
                "cognito-sync:*"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}
'''
iamClient.put_role_policy(
    RoleName='MyRole',
    PolicyName='Policy_Of_MyRole',
    PolicyDocument=policy
)

Cause

Apparently, the cause was that the first line of the here document had a line break. After changing the policy setting line as shown below, it can be set normally.

policy = '''{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "mobileanalytics:PutEvents",
                "cognito-sync:*"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}
'''

MalformedPolicyDocumentException occurred when put_role_policy

Cause