Hi All, I have been using Cloudbreak for deploying my cluster in AWS intensively. Recently, I was trying to use Periscope auto-scaling feature. This feature is very essential for our organisation as the cluster needs to autoscale based on certain yarn metrics. A more detailed description of my problem is as below, I use a ten node cluster with replication factor 3. I have 7 slave nodes running in my cluster. When I scale up using the metrics provided by Periscope I found it very smoothly scaling up, elegantly. The problem occurs when I try to downscale. The first time I downscale by one node, the decommissioning happens smoothly and the node gets removed. The next request to scale down by one node triggers the downscale operation successfully but, fails internally with the following error message "Text must not be null" with an IllegalArgumentException. I have attached the stacktrace in the file attached, a short description about the exception is below, cloudbreak_1 | 2016-01-15 16:14:08,107 [reactorDispatcher-9] accept:38 INFO c.s.c.s.e.CloudbreakEventHandler - [owner:undefined] [type:CLOUDBREAKEVENTDATA] [id:undefined] [name:undefined] Sending notification with data: CloudbreakEvent{id=467, eventType='AVAILABLE', eventTimestamp=Fri Jan 15 16:14:08 UTC 2016, eventMessage='New node(s) could not be removed to the cluster. Reason java.lang.IllegalArgumentException: Text must not be null', owner='1b534ac9-8c83-4f18-84d2-515caca7f958', account='seq1234567', cloud='AWS', region='AP_SOUTHEAST_1', blueprintName='hdp-small-default', instanceGroup='null', blueprintId=4, stackId=12} According to my judgement, the instanceGroup field is set to null internally eventhough, I mention to scale down a slave node. Can some one guide through on how to fix this issue? Your help will be much appreciated. Thank you. Best, Ramprasad S Big data Engineer - Affle Singapore. short-stacktrace.txt ... View more