Bug Reporting

All bugs should be filed in the GitHub main Emscripten repository Issue Tracker.

Please supply as much relevant information as possible, including:

  • Original source code.

  • Generated bitcode (.bc, .o or .ll)

  • Environment information — including emcc and clang versions (as reported by emcc -v).

  • Error symptoms.

  • Proposed solutions, ideally with a pull request.


Compile with EMCC_DEBUG=1 and grab the /tmp/emscripten_temp/emcc-* files (these include the bitcode and JavaScript in several stages). Note that the emscripten_temp directory should be emptied manually first, so it only contains new content!

LLVM, wasm-ld, clang, Binaryen bugs

If uncertain, bugs can always be posted to the main repository. But if you are sure a bug is in an upstream project, you can file it there:

Pull requests must (of course) go to the proper repository.

Site and documentation bugs

Documentation (site) bugs should be filed in the same Issue Tracker.

Include relevant information including:

  • The URL and title of the affected page(s).

  • A description of the problem.

  • Suggestions for a possible solution.


The Page bug link on the bottom-right of every page opens the Issue Tracker pre-seeded with the current page URL and title.