66

I just downloaded Xcode 6 & played with it a bit.

After switching back to previous version of Xcode and running in simulator, I keep getting this error.

Unable to determine simulator device to boot.

How do we resolve this?

Thanks in advance.

footyapps27
  • 3,982
  • 2
  • 25
  • 42

9 Answers9

173

Make sure you have only one iOS Simulator instance running in the Dock.

Aaron Brager
  • 65,323
  • 19
  • 161
  • 287
MarekR
  • 2,410
  • 1
  • 14
  • 10
  • 2
    @DayanGonzalez quit all instances of Xcode and reopen. – Kyle Clegg Jun 12 '14 at 20:43
  • 1
    This worked for me. I had an existing instance of iOS Simulator running that was launched with XCode 6 beta, so when I closed that and tried to launch again from Xcode 5, it worked. Thanks. – Brian S Jul 22 '14 at 18:14
  • 2
    I had another instance of iOS Simulator running, but it didn't appear in the dock. I used Activity Monitor to find and quit it, and that cleared things up. – lyricsboy Jul 28 '14 at 04:20
  • I have both Xcode 9 and Xcode 8 installed. I had Xcode 8 open and somehow I lost my simulator even though Xcode 9 was never open. I tried a bunch of other things but this 100% worked. I shut down the simulator, shut down Xcode, restarted my cpu, then opened Xcode 8 and all my simulators appeared. – Lance Samaria Oct 24 '17 at 19:16
56

There was a simple answer to this for me:

  1. Open the simulator via Xcode -> Open Developer Tool -> iOS simulator (even if it can't launch, the app will be open).
  2. With the simulator app open, go to Hardware -> Device -> Manage Devices.
  3. Add any missing simulators with the plus button (all of mine were missing for some reason).
thegreenpizza
  • 1,440
  • 13
  • 8
2

I've faced same issue and solved by below steps:

1) Move xcode6-beta into application folder

2) Restart mac and open xcode6-beta from application folder.

Mani
  • 17,549
  • 13
  • 79
  • 100
  • I had been moving old copies of Xcode around and found my simulator app with no devices. Restarting my mac is what seemed to fix it for me. – Joseph Humfrey Sep 30 '14 at 11:07
1

I had the same problem when running from Xcode 6 beta selecting iPhone 5s. If I choose iPhone 5 or "resizable iPhone" then my app launches fine.

user3397022
  • 11
  • 1
  • I'm experiencing this issue now on Xcode 6 GM. It worked fine under beta 7, but after the upgrade, none of my simulators work now, even after deleting and re-adding them. – ray Sep 10 '14 at 14:39
1

You will not see the profiles of simulator without a rebooting of OS X.I added simulator for many times,when the rebooting finished, it shows on the device list under the simulator bar. I think this is a bug of Xcode 6 Beta

swimming
  • 11
  • 1
1

I think you have 2 simulator running in the dock. Please close another one simulator and run the project again. It might helpful for you.

Ashu
  • 3,373
  • 38
  • 34
0

In my case I had such a message just because the simulated device was still booting (longer than usually, I guess). Xcode 7.2. (This is not actually an answer to this specific question, but I came here googling the message in the title, so I am writing my note here for if someone else gets the same case as I did)

ndry
  • 181
  • 2
  • 13
0

My case wasn't about having two simulators open. It was just because having instruments open as well. Closing Instruments resolved the issue

mfaani
  • 33,269
  • 19
  • 164
  • 293
-2

I just fixed the exact same problem by removing the beta version and rebooting the computer.

bensj
  • 17
  • 1