Install failed if specify sts endpoint in the install-config.yaml file:

platform:
  aws:
    region: us-east-2
    serviceEndpoints:
    - name: sts
      url: https://sts.us-east-2.amazonaws.com

level=error msg=Error: error configuring Terraform AWS Provider: error validating provider credentials: error calling sts:GetCallerIdentity: SignatureDoesNotMatch: Credential should be scoped to a valid region. 
level=error msg=  status code: 403, request id: f4e877fe-9e90-4cba-a455-2538d489a8d0
level=error
level=error msg=  on ../../../../../../../../tmp/openshift-install-cluster-1552617948/main.tf line 11, in provider "aws":
level=error msg=  11: provider "aws" {
level=error
level=error
level=error msg=Failed to read tfstate: open /tmp/openshift-install-cluster-1552617948/terraform.cluster.tfstate: no such file or directory

4.10.z

* Always

1. Create an install-config.yaml, and specify sts endpoint 
2. Create an STS cluster 

Error: error configuring Terraform AWS Provider: error validating provider credentials: error calling sts:GetCallerIdentity: SignatureDoesNotMatch: Credential should be scoped to a valid region. 

No errors, create cluster successfully

No such issues on 4.8, 4.9, 4.11, 4.12