EDIT Jan 16 2017: We no longer recommend using UUIDs to start simulators. The OS X image has been updated to resolve the underlying issue, and using UUIDs is no longer necessary. Please check out this post for examples of how to choose the simulators by name.
Hey everyone,
this issue is for most people very likely caused by a timeout because the iOS simulator not starting fast enough.
A workaround that has been tested by us is starting the GUI simulator first with:
- xcrun instruments -w 'Select a iOS Simulator UUID' || true
- sleep 15
This is a list of possible iOS Simulator UUIDs you can use:
iPad 2 (8.4) [A4276BA9-2D38-434D-A063-A1A7DC399235] (Simulator)
iPad 2 (9.0) [2F39BEF2-E92D-498C-B2D9-29366BD8F732] (Simulator)
iPad 2 (9.3) [101B434D-924B-4C7E-B8C1-ED8B376BF7CA] (Simulator)
iPad Air (8.4) [AD005E41-F7E6-4C5F-B3B1-6C980E834739] (Simulator)
iPad Air (9.0) [42D87249-99F2-4BC1-9180-317D268C46F7] (Simulator)
iPad Air (9.3) [72F9B9E8-DC05-4450-B030-407D4B0968D9] (Simulator)
iPad Air 2 (9.0) [6E2B1E19-6466-4328-917C-16019130FDE8] (Simulator)
iPad Air 2 (9.3) [A141F49D-F20A-49B3-ACBF-A97F9FFB9B89] (Simulator)
iPad Retina (8.4) [399AEF36-5560-4C4A-AE61-03F0A81555D0] (Simulator)
iPad Retina (9.0) [A1EC86BA-49AB-414B-9C27-2D0F26A34A81] (Simulator)
iPad Retina (9.3) [A70FE3C7-756F-44BF-BE46-68663FAE2EE3] (Simulator)
iPhone 4s (8.4) [F2E9EEAB-9FCE-4109-A40F-3DD79627C985] (Simulator)
iPhone 4s (9.0) [5EF3DECC-3E8F-41A0-B2CF-DC384A66E12E] (Simulator)
iPhone 4s (9.3) [8538CCCC-80FB-4B6B-9281-222771C38FEB] (Simulator)
iPhone 5 (8.4) [C5C8EA0E-F5A8-4AF8-BBAA-385B61026A5E] (Simulator)
iPhone 5 (9.0) [24F6F5A0-343E-4C64-9F4C-B50D88F5E99E] (Simulator)
iPhone 5 (9.3) [075FB8BA-F088-4A16-89CF-4EA36BC25E7A] (Simulator)
iPhone 5s (8.4) [45BFA4E8-C0A9-4A04-9CD0-4449FE4CF40B] (Simulator)
iPhone 5s (9.0) [49DAC9E5-C129-497D-853E-D93BC4BB8A10] (Simulator)
iPhone 5s (9.3) [3011ED5C-C63A-42E6-9D91-82A39DE4AD06] (Simulator)
iPhone 6 (8.4) [65AAA024-64D5-40B9-A122-8872E3F52EC4] (Simulator)
iPhone 6 (9.0) [53600017-30F1-428A-A16A-25C6CEDBD849] (Simulator)
iPhone 6 (9.3) [547B1B63-3F66-4E5B-8001-F78F2F1CDEA7] (Simulator)
iPhone 6 Plus (8.4) [DFB14113-4697-4E2D-AD3F-B4FBA4B62969] (Simulator)
iPhone 6 Plus (9.0) [321D1CF5-2514-4897-8B09-C133602F6DB5] (Simulator)
iPhone 6 Plus (9.3) [C63728B8-89B5-4FFB-8B6E-174A2F85B47F] (Simulator)
iPhone 6s (9.0) [763DC427-F2C5-4AA4-989F-2CA944FA8F04] (Simulator)
iPhone 6s (9.3) [E8DD285C-51EE-4DB5-B326-7E927686EC36] (Simulator)
iPhone 6s Plus (9.0) [011805C3-BB7A-4785-A313-D7AD2AF6DE49] (Simulator)
iPhone 6s Plus (9.3) [019CFBB0-0086-44A7-AA41-D39182D9CE01] (Simulator)
If you still run into issues please feel free to send a support request so that I can take a look at your builds and gather more information this way.
Thanks for your patience, I really do hope that this will get rid of red builds for a lot of you!
I’ve submitted a radar to Apple. Feel free to dupe it so that we can get more attention to this issue 
Greetings,
Constantin