NEW295799
WasmGC app throws cast errors and eventually crashes only on Safari 
https://bugs.webkit.org/show_bug.cgi?id=295799
Summary WasmGC app throws cast errors and eventually crashes only on Safari
Mouad Debbar
Reported 2025-07-11 12:26:47 PDT
This is a Flutter app compiled to WasmGC: https://bouncing.web.app The app runs okay on Chrome and Firefox, no errors and no crashes. But on Safari (both iOS and Mac), the app throws a few dozen cast errors: > RuntimeError: ref.cast failed to cast reference to target heap type The app eventually crashes on Safari.
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Radar WebKit Bug Importer
Comment 1 2025-07-18 12:27:12 PDT
<rdar://problem/156166198>
Alexey Proskuryakov
Comment 2 2025-10-17 08:46:55 PDT
*** Bug 300942 has been marked as a duplicate of this bug. ***
Shu-yu Guo
Comment 3 2025-10-17 08:59:04 PDT
Hi Mouad, thanks for the report. Do you still get this error on macOS Tahoe 26? In internal testing we no longer observe this happening on Tahoe.
Mouad Debbar
Comment 4 2025-10-17 09:03:38 PDT
I'm still on Sequoia 15.7 but I tried on Safari Technology Preview (Release 230) and I'm not seeing any crash! I looked through release notes and found Release 228 enabled Wasm Memory buffer APIs and Wasm JS String builtins. Do you think those are related? I also tried on iOS 26 Safari and I'm not seeing the crash there either! Thank you :)
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