Bug 262628 – WebGL: context lost - iOS 17 Safari

• Status: RESOLVED
• Resolution: DUPLICATE
• Component: WebGL

We have a very lightweight Unity game that we've been running pretty successfully on mobile web. That said, we've just run into a pretty show-stopping issue with iOS 17 Safari. The game will work totally fine on iOS 17 Safari - but then after some combination of backgrounding, using other sites and other apps (not totally sure the exact repo) - it errors with:

"WebGL: context lost"

At this point, no matter how many times I refresh, I will always get this error. Force quitting browser and event resetting the device doesn't seem to recover it. I've also tried to do different combos of compressed builds - and nothing seems to work. The one thing that does recover is clearing the safari cache. We never encountered this issue in Safari 16 - only 17. 

It seems like this might be an issue beyond Unity - see this thread. Apparently threejs is experiencing the same: https://developer.apple.com/forums/thread/737042

[Ahmad Saleem]

I think it seems to be fixed in Safari 17.1:

https://developer.apple.com/documentation/safari-release-notes/safari-17_1-release-notes#WebGL

[Josselin Guillozet]

We also observed some "WebGL: context lost" at least on iPhone X with iOS/Safari 16.7 after moving the browser to the background.
Once we get the error, we can't create any stable WebGL context until we clear the browser data.
More generally in production, we've noticed a sharp increase of WebGL related error on Safari 16.7 and 17 (Unfortunately, we don't have specific logging to check whether it relates to "WebGL: context lost").

[Radar WebKit Bug Importer]

<rdar://problem/116813694>

[Ahmad Saleem]

Safari 17.1 is released now, do we need to keep this open since it shipped with WebGL fix.

@Alexey - any input?

[Alexey Proskuryakov]

Indeed, this should have been duped to bug 261313.

*** This bug has been marked as a duplicate of bug 261313 ***