197472 2019-05-01 13:11:43 -0700 Pyodide WASM bundle fetched but won't load ("Unhandled promise rejection"), works on FF / Chrome 2019-05-03 10:34:57 -0700 1 1 1 Unclassified WebKit WebAssembly Safari Technology Preview Mac macOS 10.14 RESOLVED FIXED InRadar P2 Normal --- 1 jdl webkit-unassigned fpizlo keith_miller webkit-bug-importer ysuzuki oldest_to_newest 1532029 0 jdl 2019-05-01 13:11:43 -0700 Using Safari Version 12.1 (14607.1.40.1.4) and the latest Safari Technology Preview (Release 80 (Safari 12.2, WebKit 14608.1.16)) on macOS 10.14.4, I am unable to run pyodide examples (though other iodide examples work). Pyodide fetches a WASM archive with Python + scientific packages cross-compiled to WebAssembly, and uses them to execute Python in the browser. For context, see https://hacks.mozilla.org/2019/04/pyodide-bringing-the-scientific-python-stack-to-the-browser/ . The only error that appears in the (devtools) console when I try to run a %% py block is [Error] Unhandled Promise Rejection: undefined (anonymous function) rejectPromise promiseReactionJob I carved out a subset of one of the Pyodide examples that reproduces this behavior here: https://alpha.iodide.io/notebooks/2154/ (Click in text field after '%% py' and "Shift-Enter" to execute.) Corresponding Pyodide bug: https://github.com/iodide-project/pyodide/issues/402 It's entirely possible this is a Pyodide bug that is being obscured by the default behavior in Firefox and Chrome, but I cannot find anywhere in the Safari Dev Tools that will expose what exactly is happening. Another pair of eyes on this would be very helpful! Thanks in advance. 1532094 1 jdl 2019-05-01 15:03:30 -0700 Also present in today's Safari Technology Preview Release 81. 1532810 2 jdl 2019-05-03 09:42:15 -0700 The underlying issue was a call to WebAssembly.compileStreaming, which is not (yet) available on Safari. I'm not sure why this was not visible from the traceback, but a debug / non-minified build showed the culprit. Closing. 1532844 3 webkit-bug-importer 2019-05-03 10:34:57 -0700 <rdar://problem/50448468>