iOS 15 + WebGL 2 issue

Hi,

I have a very weird problem, and I'm not really sure where to start searching for a solution. The problem is with the latest iOS update (15) and WebGL 2, as the title suggests.

The iOS 15 update automatically enabled WebGL 2 for its users, which should be a good thing. However, whenever I try to load any of the scenes with the racing tracks on them, the game kind of freezes. At this point the game gives me an empty screen (black) and nothing really happens. No log output, nothing. After a few minutes though, I get death messages in the browser console. Normally this would happen in a few seconds instead of minutes without controlling the car. Also note that, scenes with barely anything in them, such as only UI stuff, do seem to work.

The weird part is that when disabling WebGL 2 from the Safari settings, or forcing a WebGL 1 build-only via Unity, the game runs okay. Also, on iOS 14 with WebGL 2 enabled in browser settings it seems to work fine.

This is really all I managed to find out after trying random things for a few hours. Does someone know what could be causing this? Or how I can get some more useful information regarding what's going on? I'll try some extra things and share anything I find here.

Thanks in advance!

 

Hi,
i had the same problem. After a lot of research i found one little thing that helps. I disabled the "Lightmap Streaming" in the Player Settings and now everything works fine. Maybe this little trick helps you.
Good luck!

 

Same problem here.
My game crashes "randomly" in iOS (15.0.2) Safari. On Chrome Browser (iOS) it seems to be still working.
"Lightmap Streaming" was already disabled here without any effect :/

 

Update:
The problem seems to be the "new" Webgl2.0 support of iOS Safari.
You can disable it directly on the phone:
Settings >> Safari >> Advanced >> Experimental >> WebGl 2.0

Or set webgl1.0 in the build-settings of Unity until this issue gets fixed.

I can reproduce it now this way. Not a solution but at least a temporary workaround.

 

Thanks for your answer @Affentot. Sadly your solution didn't work for me. I ended up doing the same as @chilledbits mentioned; creating a WebGL 1.0 only build for Apple devices. This works fine for now, but hopefully this will be properly fixed in the future.

 

I'm facing the same issue.. Suddenly the WebGL application that was working fine is crashing and reloading on iOS devices
Is there a way to force iPhones/iPads to use the WebGL 1.0 ?
(My app has Auto Graphics API checked )

 

I'm also experiencing this problem, my app crashes when I tap on a button, all this button does is turn a gameobject on or off, I'm also wondering if we can force iPhones/ iPads to run WebGL 1.0 as I don't want to lose my post processing effects on android by just building for WebGL 1.0, I know how to check if the device is an iphone/ ipad from the index file but I'm unsure how to force Unity to run a specific version of WebGL on start

 

On iOS 15.1 my webGL builds won't even load and start with a TypeError: load failed.

All in all, it does not feel like apple products are supporting webGL well in any form.
Low poly games, that run on mid/low end windows/linux machines with maximum FPS tend to lag on macs.

Is there anything that unity provides to run tests with webGL on iOS devices?
I have none, so i cannot even debug these problems.

 

I have the same problem as mentioned above.
When I tried all the suggestions above (Disable the "new" WebGL 2 / Lightmap Streaming - OFF) the only way to get it working on IOS (version 15.01) was to build my project to WebGL 1...
Hope it will be fixed soon.

After I updated my IOS to version 15.02 beta the Unity build WebGL 2.0 finally works!

 

I can confirm that with iOS 15.2 (not 15.02) this seems to be not an issue anymore.

 

Hi! I have a similar problem when running on iOS 15.4 beta (everything works fine on 15.3). I've tried all the suggestions posted here before, but with no success. I'm using Unity Editor 2021.2.10f1.
As soon as I add a button to my scene, which prompts me to install the TextMeshPro essentials package, I'm no longer able to load my game (even on very high-end devices).
I've attached the logs from one of the devices.
Is there a fix for this? Please let me know if you'd like me to provide any more info.

Thank you!
- David

 

Hey, I'm using unity 2022.1.0b9 and am having similar issues on IOS 15, after finishing loading it immediately gives an error Out of bounds memory access. I tried with empty scenes and changing compression values but nothing fixes this issue.

 

Yes 15.4!

 

This would be great thanks, On 15.4, disabling WebGL 2.0 and WebGL on Metal in Safari experiemental settings does not resolve the Out of Bounds error on loading.

 

Thank you for keeping us updated!

I’m curious if we’ll need to wait for a new release of iOS until this is resolved.

Is there perhaps a workaround we can implement in the meantime?

 

We tested with Unity2021.2.15f1 and Unity2022.1.0b11.

Projects with only simple components such as Main Camera, Directional Light, and Cube loaded successfully, but when we added Image or PlayableDirector components, the loading stopped halfway through.
(Runtime Error: Out of bonunds memory access)

We also found that the problematic components generate errors when the object is called.
In other words, the problem is not caused by being included in the project, but by being used.

Also, the size of WASM in that case did not exceed 9MB either, but was about 5.3MB, and the total size of the build was about 6.8MB.

These behaviors seem very strange and do not seem to be an Apple-only problem.

 

I have tested with several unity versions and build sizes. It doesn't affect by the binary size. I can make it run with build sizes over 15 MB as well. How did I make it run is a different story: I added a

Code (JavaScript):

1. debugger;

to somewhere in js code. If I wait enough and press continue on my js web console it started working correctly without any wasm issue. WebGL 2 issues still remain so I was forced to work it with WebGL 1.

 

That's an interesting finding @sercand - sounds like it might be something to do with the wasm tiering-up to a higher JIT whilst executing that causes the problem. I'm still digging for workarounds (and also pushing Apple on the bug report Brendan linked) as this is a pretty major issue for us.

 

@brendanduncan_u3d - Any chance you could try a -s WASM=0 build? Would probably be big and slow, but might actually be functional. I'm trying to dive in and debug what's going on with your examples from the webkit bug but don't know the Unity webgl build system, and don't have Unity installed here at the moment

 

Thanks for the update Brendan.

I had noticed the stack cookie check code was where things were failing on your minimal clear-color example, but I believe other projects show other errors. Looks most likely just a Safari VM bug that corrupts random stuff when running perfectly valid code, but obviously if you are able to narrow it down to a trigger in the Unity code that can be fixed that would be brilliant.

Is it possible for users to customise the emscripten command lines for the webgl build? There's various flags and options that I'd be happy to play around with if so. I added an issue on emscripten GitHub just mainly to get their advice too - that's here: https://github.com/emscripten-core/emscripten/issues/16526

I'm also dedicated to this at the moment, looking for workarounds. My current plan:
1 - Try a wasm2js converted build (which I expect to be functional but perhaps too slow to be useful)
2 - Look at wasm-split to see if we can separate the wasm into smaller modules and if that avoids the bug
3 - Try to bisect in the open-source webkit code to identify the breaking commit (if it is in fact broken there) to give better hints to Apple engineers

We're also leveraging any contacts we can find to bring more pressure on Apple in the hope for a fix and a point release ASAP.

 

Thanks for the hints. Assigned myself a seat and downloading the editor now. Looks like the -s MAYBE_WASM2JS only introduces minimal runtime changes, so I'm still trying to patch your built examples first.

Haven't tried to repro with open-source WebKit yet as finding a workaround is priority #1. Apple in general are very opaque on this stuff, but at least some in the Safari team work slightly more collaboratively on the webkit bug tracker. Not the case yet on this bug, but I live in hope - we did get a few other critical things fixed during the iOS 15.4 beta phase, but unfortunately this one wasn't on our radar until Wednesday

 

Thanks for the hard work Brendan! If I may ask, how will the fix be rolled out/shared with? I am too facing this issue where my users who are playing our browser based Unity WebGL games and upgraded to the recent iOS 15.4 build could not have their games loaded and getting stuck at 90%

 

Great updates Brendan, thanks for your great work on this so far. On the graphics regressions, is webgl1 still working well enough? We noticed some broken three.js webgl2 content seemingly triggered by the use of SRGB8_ALPHA8 textures in the beta. Haven't yet noticed any regressions with our webgl1 content at least.

I've managed to get a wasm2js build of your minimal clear-color developer build working on iOS 15.4 too, and in a way where it's opt in via a ?_wasm2js=1 query string for testing. Looking into applying the same thing to a more complex example project now.

 

Could you post the workaround, so we can get our Games to work temporarily?

Oh and thank you for all your hard work!

 

Thanks Brendan but i can't find the Library/Bee/artifacts/WebGL/il2cpp in my project directory

Edit: My game now can launch and won't stuck in 99% but after playing for a while the game UI started to flicker which doesn't happen before.

 

Dunno if it works 100%, but your solution @brendanduncan_u3d worked for me, many thanks!

 

Awesome fix @brendanduncan_u3d.
This seems to work for me as well, building on windows for WebGL. I was skeptical if clang macro would work on windows but Unity seems to be taking it well.

 

@brendanduncan_u3d Thanks for that workaround! We have many games which we have building through Unity Cloud Build and automatically deploy successful builds. It'd take a lot of time for us to start doing that manually. Any chance you guys could update Unity Cloud Build with this workaround temporarily?

 

Thank you for this! The workaround seems to work with no noticeable bugs. Do you reckon there will be any performance impact caused by this?

 

We too tried the workaround and were able to activate it successfully. Thank you very much. We appreciate your efforts.

In Unity 2020.3.30 with the improvements added, the build failed if Enable Exceptions in Publish Settings is set to None.
When I changed it back to Explicitly Throw Exceptions Only, the build succeeded.
This did not seem to happen with Unity2021.2.15.

I found during testing that only iOS15.4 does not seem to refresh the Canvas UI properly.
It still seems that there are still many bugs in the WebGL functionality itself in iOS15.4 since it occurs only in iOS15.4.