HTTP Load Balancer Custom Error Page

Question

Is there a way currently to set a custom error page if the load balancer does not have any children to distribute to either because of load or if they are down?

Answer 1

There is no out of the box solution for that. A load balancer cannot serve content itself, it redirects traffic for instances that can do that.

You can however try to explore the possiblity to serve an error page from Google Cloud Storage :

Load Balancing to Cloud Storage

Content based example

But you'll to figure out a way to redirect to cloud storage only when no other instances are responding. I hope this helps.