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Fixed in 2021.1.X

Fixed in 2019.4.X, 2020.3.X



Found in




Issue ID




[WebGL] [iOS 13] Application on browser crashes when trying to minimize the browser 'Out of bounds Trunc operation'



Reproduction steps:
1. Open user's attached project and build it for WebGL 2 (read note 7)
2. Host the built application (read edits for how to do it on your local network, note 1)
3. Open the Application in the browser of an iOS device
4. Minimize the browser by sliding your finger up from the bottom of the screen (note 4)
5. Maximize the browser

Unexpected behavior: the WebGL Application has crashed (image of crash attached)

6. If the Application does not crash, restart the browser, wait for the Application to load, and to steps 4, 5, 6 again (note 3)

Reproducible with: 2020.1.0b16, 2020.2.0a18
Could not test with 2018.4 2019.4 because the server only shows files in the browser and not the Application, 2020.1.0a1 because the Application does not complete loading in the browser (the page is created with the UI elements but the Game itself does not launch)

Devices tested:
Reproducible with:
VLNQA00310 iPad Pro 12.9 (iOS 13.4.1)
Not reproducible with:
OnePlus A5000 (Android 9, Oxygen 9.0.11), Snapdragon 835, Adreno 540
iPhone XR (iOS 13.4.1)

Not reproducible with WebGL 1.0 Graphics API

Reproducible with: Google Chrome (the difference between other browsers is that the application is maximized in Chrome)
Not reproducible with: Safari, Firefox

1. Look for 'To host the application:' for step 2
2. All testing was done in release builds since the issue does not reproduce on a development build
3. The application only crashes once and after refreshing the page it does not crash again
4. The application only crashes when sliding from the bottom to the top and does not crash when trying to minimize it with a button or any other way
5. A video is attached (VID_20200722_111709.mp4)
6. The issue is possible to test only with iOS 13+
7. Customer mentioned that the issue is also reproducible with WebGL 1 if using Safari

  1. Resolution Note (fix version 2021.1):

    Fixed in 2021.1.0a2

  2. Resolution Note (fix version 2020.3):

    Fixed in 2020.3.16f1.804

Comments (7)

  1. motoBTS

    Dec 16, 2020 02:48

    Hey MARKS4, I looked at your 2nd crash example. How do you get the webGL app to start in fullscreen on iPhone/iPad? I’ve been trying to figure that out. Thanks!

  2. amateurd

    Sep 03, 2020 09:43

    Workaround: in Publishing Settings, set "WebAssembly Arithmetic Exceptions" to "Ignore" and the problem seems to go away.

  3. amateurd

    Aug 28, 2020 09:44

    Trial and error shows this only seems to happen when the height of the WebGL canvas is within 50pixels of the browser's innerHeight.

    No idea why, but putting here in case it helps someone with a workaround.

  4. amateurd

    Aug 28, 2020 06:49

    I notice this does not happen unless the WebGL content is in focus: i.e. if a text box or button on the same page is focused then it doesn’t crash.

  5. amateurd

    Aug 28, 2020 06:39

    This is a regression, does not happen in versions before the recent changes to WebGL. Games which previously successfully loaded with WebGL on Safari on iOS 13 now have this problem.

  6. Marks4

    Aug 12, 2020 22:38

    Also, this happens when using WebGL 1.0 as well.

  7. Marks4

    Aug 12, 2020 17:44

    It happens on Safari, and another easy way to make the problem happen is to add a shortcut to the homescreen and try to minimize. Below are 2 gifs showing how to reproduce the problem.

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