My load balancer target group shows up as "Not available" - how do I debug this further?

Question

I've created a Network Load balancer and a target group. Then I try to create a listener for the load balancer, but the target group is showing up as "Not available" in the pulldown menu.

What can be my next step to debug this? Much appreciate the help.

Picture: https://ibin.co/w800/3vKxtcYYs3mg.jpg

Answer 1

The UI appears to have changed, but I had a similar problem (NLB showing an unassigned target group grayed out in the listener's dropdown). When starting over, I had to make sure that the target group protocol was TCP or whichever protocol the balancer would be forwarding to.

The Add Listener page also has Protocol and Port fields, and any groups with the wrong protocol were unavailable. Selecting an available target group and then changing to a different protocol caused the page to show an error like "TCP_UDP listeners cannot forward traffic to TCP target groups. You must select a compatible target group or change the listener protocol."