We are hitting a re-occurring issue now with a particular configuration. From the log can you see why this error is being frequently displayed:

We are running 6.1.17.

2016-06-06 12:53:59,275 [pool-1-thread-9] INFO com.pmease.quickbuild.DefaultBuildEngine - Processing build request (configuration: /CI/ , request id:821b276a-6638-4f2e-8be9-7a0a872d09f2)
2016-06-06 12:53:59,280 [pool-1-thread-9] INFO com.pmease.quickbuild.DefaultBuildEngine - Checking build condition on node (address: -AGENT06:8811, ip: 10.64.105.142)...
2016-06-06 12:54:10,382 [pool-1-thread-42] ERROR com.pmease.quickbuild.grid.GridTaskFuture - Unable to find job (job class: com.pmease.quickbuild.CheckConditionJob, job id: 02dd2911-0fbe-4c18-9662-81783b25dd7c, node: -AGENT02:8811)
2016-06-06 12:54:10,487 [pool-1-thread-42] ERROR com.pmease.quickbuild.DefaultBuildEngine - Error processing build request.
java.lang.RuntimeException: Error executing check condition job.
at com.pmease.quickbuild.CheckConditionTask.reduce(CheckConditionTask.java:39)
at com.pmease.quickbuild.CheckConditionTask.reduce(CheckConditionTask.java:16)
at com.pmease.quickbuild.grid.GridTaskFuture.get(GridTaskFuture.java:102)
at com.pmease.quickbuild.grid.GridTaskFuture.get(GridTaskFuture.java:106)
at com.pmease.quickbuild.DefaultBuildEngine.process(DefaultBuildEngine.java:332)
at com.pmease.quickbuild.DefaultBuildEngine.access$000(DefaultBuildEngine.java:139)
at com.pmease.quickbuild.DefaultBuildEngine$2.run(DefaultBuildEngine.java:1143)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: com.pmease.quickbuild.QuickbuildException: Unable to find job '02dd2911-0fbe-4c18-9662-81783b25dd7c' on node '<removed>-AGENT02:8811'.
at com.pmease.quickbuild.grid.GridTaskFuture.testJobs(GridTaskFuture.java:42)
at com.pmease.quickbuild.grid.GridTaskFuture.get(GridTaskFuture.java:84)
... 7 more
2016-06-06 12:54:10,491 [pool-1-thread-42] INFO com.pmease.quickbuild.DefaultBuildEngine - Processing buil