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Fixed in 2018.1

Fixed in 2017.1, 2017.2, 2017.3



Found in


Issue ID




[iOS11] 'API called on a background thread: - [UIApplication delegate] > UnityCurrentOrientation' on launch in an empty project



Reproduction steps:
1. Create a new Unity project.
2. Build and run to iOS device.
3. Check the Xcode console:

Main Thread Checker: UI API called on a background thread: -[UIApplication delegate]
PID: 2204, TID: 2872809, Thread name: (none), Queue name: NSOperationQueue 0x1c4039300 (QOS: UNSPECIFIED), QoS: 0
4 ProductName 0x00000001011f5fbc UnityCurrentOrientation + 60
5 ProductName 0x00000001011e3e14 __UnityCoreMotionStart_block_invoke + 108
6 Foundation 0x00000001855ba310 <redacted> + 16
7 Foundation 0x00000001854fa9e4 <redacted> + 72

18 libdispatch.dylib 0x00000001845821c8 <redacted> + 596
19 libdispatch.dylib 0x0000000184581f10 <redacted> + 120
20 libsystem_pthread.dylib 0x000000018481b130 _pthread_wqthread + 1268
21 libsystem_pthread.dylib 0x000000018481ac30 start_wqthread + 4

Reproduced with:
5.6.3p4, 2017.1.2f1, 2017.2.0f2, 2017.3.0b3
iPad Mini 4 iOS 11.0
iPhone 6s iOS 11.0

Not reproducible with:
iPad 5 iOS 10.3.3
iPad Air 2 iOS 9.2

Comments (15)

  1. 666883f2676596130be878ff0a540aba?d=mm


    May 07, 2018 08:49

    It's also happening with Unity 5.6. Please do post when fixed.

    It seems that it started happening after we changed the splash screen and orientation settings...

  2. 48259620d92e7333f003fe34557eb4f0?d=mm


    Mar 17, 2018 08:54

    I have this bug. My code compiles and runs fine - I have yet to release it on the app store. Will in-app purchases work? Or does this bug have to be resolved?

  3. 0b4910e870496ad2d680bf6fac10196f?d=mm


    Jan 19, 2018 04:03

    This is definitely still in 2017.3. I was able to fix it by disabling Accelerometer which I don't need. I did this in the iOS player settings.

  4. 71cb5bdc73bba20d73fc4c24f0fdbdfe?d=mm


    Jan 18, 2018 09:00

    This is a showstopper. It seems to add 13 extra seconds to game loading time.

  5. Cb15702dd107b280b5b648ebd84cbdcd?d=mm


    Jan 12, 2018 18:29

    I am having this issue with Unity 5.6.4 p4 and XCode 9.2. Game does not crash, but nothing properly displayed in screen.

  6. D80ff4627164f167f1e40af38ae81753?d=mm


    Jan 10, 2018 18:05

    You might try setting the Accelerometer Frequency to Disabled in Project Settings->Other Settings, if you do not need the Accelerometer.

    I have four projects all using 2017.2.1.p1. I have three do not have the exceptions on startup while the forth one does. The only difference I found was that the Accelerometer Frequency is set to Disabled for the three projects. So as a test, I set the Accelerometer Frequency to Disabled in the forth project and the exception on startup disappeared. Sadly, for that project I need it set to 60.

    I just did a quick test of 2017.3.0.f0 and the exception on startup does not occur when Accelerometer Frequency is set to Disabled.

  7. 64645a9f537ff1e95a45b9b3b6860196?d=mm


    Jan 09, 2018 22:20

    We are seeing this issue still. Why is it marked fixed?

  8. 6194fe934f936d98aff8698232b59b0a?d=mm


    Jan 04, 2018 02:26

    I still have the same problem in 2017.3.0p1. Does anyone knows a workaround?? Thanks!

  9. 995e9653cd99d97124d5963ae6101166?d=mm


    Dec 29, 2017 17:23

    Still there with 2017.3.0f3

  10. 34ff5e0905fc05fe0af5d69685f240dc?d=mm


    Dec 07, 2017 06:04

    Anyone know what release fixed this issue?

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