Xcode bot test session exited without completing

Question

I've been getting semi random instances of...

Test operation failure: Test session exited(-1) without completing.
_finishWithError:Error Domain=IDEUnitTestsOperationsObserverErrorDomain Code=3 "Test session exited(-1) without completing." UserInfo=0x7fcd0a83c2c0 {NSLocalizedDescription=Test session exited(-1) without completing.} didCancel: 1
Finished syncing device diagnostic logs after 0.0s.

errors on my Xcode CI bots. I haven't got a clue on how to fix this. These has been attempted without any positive result

• Cleaning the DerivedData folder of the Xcode build server – all folder named DerivedData within /Library/Developer/XcodeServer
• Restarting the server machine

Any ideas how to fix this?

Some environment:

• Xcode 6.3.2
• iOS SDK 8.3
• OS X 10.10.3
• Server 4.0.3

Clip

Are you testing on devices or simulators? I've seen this on devices that randomly disconnected due to a faulty cable. – Osculate

@Osculate simulator only. I finally gave up and reset the entire CI environment, which fixed it for now. – Clip

just a question: why are you using xcode 6? – Insured

The same problem. any ideas how to fix it? – Ernie

Did you solve your problem? I fight with this for a year:) – Ernie

I also had a similar problem running tests on all 34 simulators (iOS 8-10) on an imac 2009. Some simulators just took too long to boot and the integration threw a timeout. On faster macs it worked. – Aport