Latest emscripten doesnt work on examples

The newest version 1.39.4 does not seem to work with ubuntu for me.
So I use

git clone
cd emsdk
./emsdk install 1.39.3-fastcomp
./emsdk activate 1.39.3-fastcomp
source ./


git clone
cd emsdk
./emsdk install latest-fastcomp
./emsdk activate latest-fastcomp
source ./

works again but i had to change
Here is the edited file:

can you send a pull request with the changes?

@arturo I will , hope my changes do not break anything that was working before :wink:
But so far it seems to work fine.

Could that mean that I could use DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR=1 if the Emscripten .html template gets updated according to the changelog?

From the Emscripten Changelog 1.39.5:

    With this change the old deprecated HTML5 API event target lookup behavior is
    disabled. There is no “Module.canvas” object, no magic “null” default handling,
    and DOM element ‘target’ parameters are taken to refer to CSS selectors, instead
    of referring to DOM IDs. For more information see:!msg/emscripten-discuss/xScZ_LRIByk/_gEy67utDgAJ

yes it seems they’ve changed the way to handle events so changing the template would allow it to work without enabling this flag. that would be of course better but if you are not sure on how to update the template, sending a PR with this flag and opening an issue explaining this would be also super useful

1 Like

Hi Arturo, I made a pull request:
but “some checks were not successful”. Yes, it seems I am not sure how to update the template.html, but I am also not sure how to make a PR without submitting some code :wink:

Hello again,

I manage to build a Docker image running Ubuntu with OF and emsdk. This image allow me to compile OF project in webAssembly, but also under Windows. A folder on Windows is shared with the docker image. When I create a new project, I ask projectGenerator to build project for Visual Studio and linux q-creator.

I put everything in GitHub

It comes with a quick start. This should be reproductible with WSL.

I had to build against version 1.39.4-fastcomp sdk of emscripten, not latest. There is issues with 1.39.5 related to how events are passed between js and WEBASM I think. Like noted in previous post of this thread.

I have an issue with fullscreen button that throw an error, also due to event handling I think.

I hope to get time to look at that.


I also wanted to mention that I had to use this work around to make use of ofFbo with Emscripten:

1 Like


I’m having trouble running emscripten apps (but seem to be compiling without errors). Wondering if these PRs and instructions are still valid? cc @theo



Hello, I am following your guide on git hub. When I run the command “./build.ps1” in PowerShell, It runs fine, but then it freezes when it asks for my location. I can not input my geographical area when it prompts me to. Any suggestions?

Hi all, wanted to chime in here saying the 3DPrimitivesExample no longer builds with emsdk activate latest. Error log:

It builds with latestfastcomp, but the site errors out:

Also it seems the fastcomp version is deprecated, lots of warnings when trying to use it: em++: warning: the fastomp compiler is deprecated. Please switch to the upstream llvm backend as soon as possible and open issues if you have trouble doing so [-Wfastcomp]

The recommended alternative emsdk is no longer available, either Error: No tool or SDK found by name 'sdk-incoming-64bit'.

I’m getting following errors which are a bit different from above. Running emcc -v gives 1.40.1, on ubuntu 20.04, and OF 0.11.0.

Have tried re-installing, and done (I think) most of the Linux-relevant suggestions before and am able to compile super-simple stuff (‘hello world’) from the emscripten documentation, but seemingly nothing using OF.

Any suggestions welcome!
Thank you

make: make
Compiling OF library for Release
make[1]: Entering directory ‘/home/ukc/of_v0.11.0_linux64gcc6_release/libs/openFrameworksCompiled/project’
make[1]: Leaving directory ‘/home/ukc/of_v0.11.0_linux64gcc6_release/libs/openFrameworksCompiled/project’

Compiling 3DPrimitivesExample for Release
make[1]: Entering directory ‘/home/ukc/of_v0.11.0_linux64gcc6_release/examples/3d/3DPrimitivesExample’
make[2]: Entering directory ‘/home/ukc/of_v0.11.0_linux64gcc6_release/examples/3d/3DPrimitivesExample’

 compiling done
 to launch the application on the default browser, run:

 emrun bin/3DPrimitivesExample.html
 some browsers, like safari, don't support webgl

make[2]: *** [/home/ukc/of_v0.11.0_linux64gcc6_release/libs/openFrameworksCompiled/project/emscripten/ afterplatform] Error 127
make[2]: Leaving directory ‘/home/ukc/of_v0.11.0_linux64gcc6_release/examples/3d/3DPrimitivesExample’
make[1]: *** [/home/ukc/of_v0.11.0_linux64gcc6_release/libs/openFrameworksCompiled/project/makefileCommon/ ReleaseABI] Error 2
make[1]: Leaving directory ‘/home/ukc/of_v0.11.0_linux64gcc6_release/examples/3d/3DPrimitivesExample’
make: *** [/home/ukc/of_v0.11.0_linux64gcc6_release/libs/openFrameworksCompiled/project/makefileCommon/ Release] Error 2

Sorry the actual error is when I start a Firefox (or Chrome) browser, I get an error and no image, even though I have a local server running. The error I get is: ‘[notice ] ofxAppEmscriptenWindow: Got 1 display configs’

Same here (Ubuntu and OSX), did you find any solution?

I tried to compile with the current Emscripten 2.0.26 and OF 0.11.2.
I changed this in Fix emscripten to use non deprecated emsdk docker image by ofTheo · Pull Request #6665 · openframeworks/openFrameworks · GitHub
And I get the error:
wasm-ld: error: /home/jonathan/Schreibtisch/of_v20210719_linux64gcc6_release/libs/freetype/lib/emscripten/libfreetype.bc: unexpected table definition(s) without corresponding symbol-table entries.
Anyhow, it is working fine with Emscripten 1.40.1 (except the fullscreen issue and not antialiasing 2d-shapes), so it is not really an issue for me, but it would be great to use the newer Emscripten versions eventually. Regarding the fullscreen issue: If I use a lowercase s in Module.requestFullscreen then it changes to fullscreen, but a black one: lowercase_s_in_fullscreen by juj · Pull Request #4318 · emscripten-core/emscripten · GitHub
openFrameworks/template.html at master · openframeworks/openFrameworks · GitHub

Actually it works with Emscripten 2.0.6 with this change Fix emscripten to use non deprecated emsdk docker image by ofTheo · Pull Request #6665 · openframeworks/openFrameworks · GitHub :

git clone
cd emsdk
./emsdk install sdk-2.0.6-64bit
./emsdk activate sdk-2.0.6-64bit
source ./

With the same result as 1.40.0 (everything works fine, except fullscreen and antialiasing of 2d-shapes).
This could point into a direction why newer versions do not work (current is 2.0.26): Compiler error with malformed symbol generated · Issue #12551 · emscripten-core/emscripten · GitHub
Ensure EH does not change code after linking by aheejin · Pull Request #12493 · emscripten-core/emscripten · GitHub
My example:

From the Emscripten changelog:

2.0.7: 10/13/2020
- Don't run Binaryen postprocessing for Emscripten EH/SjLj. This lets us avoid
  running `wasm-emscripten-finalize` just for C++ exceptions or longjmp. This
  is an ABI change. (#12399)

I followed these instructions, the right sdk version, same of version 0.11.2-1 patching the file as in the PR.

and now I get the following error when compiling

wasm-ld: error: unknown argument: --as-needed

Any ideas?

@hypermodernist perhaps you need this steps after installing:

From 2.0.7 until (approximately) 2.0.12 I get this error message:

emscripten:ERROR: emscript: failure to parse metadata output from wasm-emscripten-finalize. raw output is: 
  "tableSize": 11127,
  "initializers": [
  "declares": [


  "namedGlobals": {
  "invokeFuncs": [
  "mainReadsParams": 0,
  "features": [

Traceback (most recent call last):
  File "/home/jonathan/emsdk/upstream/emscripten/", line 14, in <module>
  File "/home/jonathan/emsdk/upstream/emscripten/", line 2156, in run
    post_link(options, wasm_target, wasm_target, target)
  File "/home/jonathan/emsdk/upstream/emscripten/", line 2185, in post_link, wasm_target, final_js, memfile)
  File "/home/jonathan/emsdk/upstream/emscripten/", line 876, in run
    return temp_files.run_and_clean(lambda: emscript(
  File "/home/jonathan/emsdk/upstream/emscripten/tools/", line 104, in run_and_clean
    return func()
  File "/home/jonathan/emsdk/upstream/emscripten/", line 876, in <lambda>
    return temp_files.run_and_clean(lambda: emscript(
  File "/home/jonathan/emsdk/upstream/emscripten/", line 319, in emscript
    metadata = finalize_wasm(in_wasm, out_wasm, memfile, DEBUG)
  File "/home/jonathan/emsdk/upstream/emscripten/", line 484, in finalize_wasm
    return load_metadata_wasm(stdout, DEBUG)
  File "/home/jonathan/emsdk/upstream/emscripten/", line 786, in load_metadata_wasm
    metadata_json = json.loads(metadata_raw)
  File "/usr/lib/python3.8/json/", line 357, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.8/json/", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.8/json/", line 353, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting ',' delimiter: line 197 column 22 (char 5228)

Thank you for your response
I did the steps you suggested before I tried. I still get that error message.
Perhaps I will try from git master instead of from AUR latest of version