Unable to determine simulator device to boot. - Xcode

Question

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.

Fick

Answer 1

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

Pages

@DayanGonzalez quit all instances of Xcode and reopen. – Quarters

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. – Advocacy

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. – Incurious

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. – Stereo

Answer 2

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).

Pretense

Thanks man! Had to restore from a backup and all my simulators were missing – Declinometer

Excellent. Took me all day to figure this out, installing and unistalling, until I read this. – Reiff

Thank you for solution. I have been trying to solve that problem since 5 hours. Terrible update for XCode 6.1 really! – Bugger

Answer 3

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.

Reagan

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. – Mcelrath

Answer 4

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.

Outweigh

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. – Underling

Answer 5

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

Faitour

Answer 6

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.

Cookshop

Answer 7

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)

Jocosity

Answer 8

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

Sheffield

Answer 9

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

Vizor