python code gets error: botocore.exceptions.NoCredentialsError: Unable to locate credentials

Question

I got a error like this botocore.exceptions.NoCredentialsError: Unable to locate credentials when I was running the following code:

# setup AWS Connection details
awsSession = boto3.Session(profile_name="opsdev")

def getInfoFromDynamoDB(service):
    client = awsSession.client('kms')
    dynamodb = awsSession.resource('dynamodb')
    table = dynamodb.Table('app_info')

    response = table.get_item(
        Key={
        # here is where the eroor comes out as "Unable to locate credentials"
        "service": str(service)
    }
)

MongodbInfo = getInfoFromDynamoDB('Mongodb')

I have also tried not specify the profile name, but it gives the same error

awsSession = boto3.Session()

So basically in our organization, there is a group called DEV that have the right to query from dynamoDb and I am going to assume myself as DEV role then play with DynamoDB and we use MFA as well.

I have done some researches in the boto documentation and StackOverflow. I think I can't specify keys manually because I have a role to assume and I will be using the assumed role key info as suggested in this post Boto3 Error: botocore.exceptions.NoCredentialsError: Unable to locate credentials

Here is my config file:

[default]
aws_access_key_id = xxxxxxxxxxxxxxxxQQ
aws_secret_access_key = xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxGf

[profile opsdev]
output = json
role_arn = arn:aws:iam::123456789123:role/DEV
mfa_serial = arn:aws:iam::123456789123:mfa/abc@def.com
source_profile = default
region = us-east-1

Here is my credentials file

[default]
aws_access_key_id = xxxxxxxxxxxxxxxxQQ
aws_secret_access_key = xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxGf
[opsdev]
role_arn = arn:aws:iam::123456789123:role/DEV
mfa_serial = arn:aws:iam::123456789123:mfa/abc@def.com
source_profile = default
region = us-east-1

I have tried not having opsdev profile part in credentials, not working still

When I was invoking a role like this:

 aws --profile=role s3 ls --debug

There is no error generated but a list of Bucket names

I tried

$ aws sts assume-role --role-arn arn:aws:iam::709957318545:role/DEV_OperationsDevelopers --role-session-name testAssumeRole

An error occurred (AccessDenied) when calling the AssumeRole operation: User: arn:aws:sts::123456789123:assumed-role/DEV/AWS-CLI-session-987654321987 is not authoried to perform: sts:AssumeRole on resource:arn:aws:iam::123456789123:role/DEV

$ aws configure list
Name                    Value             Type    Location
----                    -----             ----    --------
profile                   opsdev           manual    --profile
access_key     ****************xxIQ      assume-role
secret_key     ****************xxf0      assume-role
region                us-east-1      config-file    ~/.aws/config

$ aws sts get-caller-identity --profile opsdev
Enter MFA code:
{
"Account": "123456789123",
"UserId": "xxxxxxxxxxxxxxxxxxxxxxxx:AWS-CLI-session-987654321",
"Arn": "arn:aws:sts::123456789123:assumed-role/DEV/AWS-CLI-session-987654321"}

And I am pretty sure my identity is able to do the assume role action, because we had a python file that prompts for the MFA code then get a MFA session, then create another session with MFA detail, at last ctreat a new session with STS Client for the assume role. Using this session is able to connect to the DynamoDB.

And help is greatly appreciated.