com.netflix.hystrix.exception.HystrixRuntimeException: ... could not be queued for execution and no fallback available.
Caused by: java.util.concurrent.RejectedExecutionException: Rejected command because thread-pool queueSize is at rejection threshold.

com.netflix.hystrix.exception.HystrixRuntimeException: ... short-circuited and no fallback available.
Caused by: java.lang.RuntimeException: Hystrix circuit short-circuited and is OPEN

com.netflix.hystrix.exception.HystrixRuntimeException: ... failed and no fallback available.
Caused by: feign.RetryableException: timeout executing POST http://localhost:8089/aaa