Your browser does not support WebAssembly Threads.

Hi,

I have a Unity project (2019.1.11f1)
I've just generated the build for WebGL with no thread support

Code (CSharp):

1. PlayerSettings.WebGL.threadsSupport = false;

However when trying load the build on Firefox, I see a dialog box showing the message: Your browser does not support WebAssembly Threads. So, the loading of the build is aborted.

Digging into the UnityLoader.js file and inspecting the web page I realised that some conditional evaluations are wrong.
At some point in the code you find:

Code (CSharp):

1. if(e.multithreading&&!UnityLoader.SystemInfo.hasWasmThreads)return void t("Your browser does not support WebAssembly Threads.");

Inspecting the values in the web console we have the following:
- !UnityLoader.SystemInfo.hasWasmThreads is boolean and evaluated as true
- e.multithreading is a string and is evaluated as "false"
- Finally, e.multithreading&&!UnityLoader.SystemInfo.hasWasmThreads is evaluated as true and the dialog box is shown.

The way to avoid this behavior is replacing e.multithreading by e.multithreading=="true"

Also found something similar earlier in the code:

Code (JavaScript):

1. n()?!UnityLoader.SystemInfo.hasThreads&&e.multithreading?r("Your browser does not support multithreading."):t()

Just in case someone has the same problem. Will also report a bug.

Regards.

 

2020 this is still here? Was getting the error in fitefox. Will try this fix thank you

 

It seems the issue is somewhere deeper, at least in 2020.1.0 (the most recent version I know to allow me to build with "PlayerSettings.WebGL.threadsSupport=true").
In <ProjectName>.loader.js, the "u.SystemInfo.hasThreads" seems to return false on all browsers, and even if I remove that check manually, I then get "Current environment does not support SharedArrayBuffer, pthreads are not available".
All my browsers are at latest versions, and I even tried enabling "Experimental WebAssembly" or "WebAssembly baseline compiler" in chrome (via about://flags). No result.

 

Anyone solved this? I tried on 2022.2 Beta and still the same problem