Getting error: Missing Authentication Token after AWS API request

Question

I am trying to call a Lambda Function through AWS API Gateway.

I've been getting this error when I tried IAM authentication, API Key Authentication and also with no authentication.

{"message":"Missing Authentication Token"} 

Some people had the same problem due to non existing endpoint. However, I've taken my endpoint directly from the Lambda Function AWS Console.

I've been trying to open the URL in the Browser and also on the Postman (with and without a header authentication: x-api-key: *****************).

Both responded with above stated error.

Answer 1

One more step: in Postman, you need to set the Authorization to AWS Signature, and then enter your AccessKey and SecretKey from your IAM user:

Postman screenshot