Why Am I Seeing the Message "No backend available"?¶
Check whether the backend service is accessible, and modify the backend service if it is inaccessible.
Check the ECS security group configurations of the backend service and verify that the required port has been enabled.
Check whether ACL configurations of the VPC restrict the communication between the API gateway and the subnet where the backend service is located.
If you use a VPC channel, check whether the service port, health check port, and backend servers of the VPC channel have been correctly configured.