AWS - Difference between ELB_5XXs and HTTP_5XXs

Question

In AWS Cloud watch, what is the difference between ELB_5xx and Http_5xx errors? And then there is also Backend_connection_errors.

Answer 1

HTTP errors served to the user can occur at either the load balancer or target level.

Any metrics that are prefixed with ELB originate at the load balancer level, there are many reasons why these can occur. For a 5XX error it could be a problem with connecting to your targets or could be that the throughput to the load balancer was too high (ELBs scale too based on traffic). More information about these errors are available in the Troubleshoot your Application Load Balancers document.

For the Http_ errors these will be coming from the target itself, essentially your application has returned this HTTP status back to the client. For debugging these you would look in your application logs to identify the root cause.