Getting 403 when connecting to a Cloud Run service when using a Serverless VPC Connector

I have a service on Cloud Run (Service A) who is trying to call another service on Cloud Run (Service B). Both the services are in us-east1. For Service B, Ingress is set to 'Allow internal traffic only' and Authentication is set to 'Allow unauthenticated invocations.

I created a Serverless VPC Connector in the same region as the services and set the IP address range to 10.8.0.0/28. 

I then connected Service A to the connector mentioned above and set 'Route only requests to private IPs through the VPC connector'.

I seem to be getting a 403 when attempting to hit the service.

https://stackoverflow.com/questions/66728206/getting-403-when-connecting-to-a-cloud-run-service-when-using-a-serverless-vpc-c March 21, 2021 at 10:07AM