Not authorized to perform: sts:AssumeRole on resource - amazon-web-services

Question

I'm trying to use kubectl to work on a EKS Cluster created from an other user.
I followed the different instructions from the documentation to create the kube config file with the command : aws eks --region eu-central-1 update-kubeconfig --name internal --role-arn arn:aws:iam::xxxxxxxxxx:role/eks_role_internal.
Then when i try to test the configuration (kubectl get svc), i'm getting the error :
could not get token: AccessDenied: User: arn:aws:iam::xxxxxxxxxxxx:user/me is not authorized to perform: sts:AssumeRole on resource: arn:aws:iam::xxxxxxxxxxxxx:role/eks_role_internal
Here is the config for the Policy :
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "VisualEditor0",
"Effect": "Allow",
"Action": "sts:AssumeRole",
"Resource": "arn:aws:iam::xxxxxxxxxxx:role/eks_role_internal"
}
]
}
And the trust relationship of the role :
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service": [
"eks.amazonaws.com",
"ec2.amazonaws.com"
]
},
"Action": "sts:AssumeRole"
}
]
}

Answer 1

The first reason getting this error message is misconfigured Trusted relationship on a role that is going to be assumed.
I also was seeing this error when the attached condition in the trusted relationship of having MFA wasn't met:
"Condition": {"Bool": {"aws:MultiFactorAuthPresent": true}}
AWS cli isn't smart enough to see this case and ask for the MFA code, it just throws that error message.