InvalidSignatureException : AWS Amplify API Requests fail

gistfile1.txt

When calling a manually calling an API Gateway Endpoint, you get a 403 Response with Response Header x-amzm-error-type:InvalidSignatureException


When configuring your endpoint with Amplify.configure({...}) (see https://docs.amplify.aws/lib/restapi/getting-started/q/platform/js#configure-your-application)

add a region:
{
...
  API: {
          endpoints: [
              {
                  name: "MyAPIGatewayAPI",
                  endpoint: "https://1234567890-abcdefgh.amazonaws.com",
                  region: "eu-central-1" // <- add this
              },
              ...
          ]
    }
 ...
 }