WebGL build failed - Unity looking for wrong version of Emscripten?

Hello! I'm having an issue building to WebGL (both my existing project and a new blank project). Part of the output of the error says it can't find a version of Emscription (1.29.0) on my computer, which is true - my PC has 1.35.9 installed. The problem is, I can't install 1.29.0 via command line because the Emscripten repo seems to no longer exist (you can try for yourself by following the steps here).

Any ideas on what I can do to fix this? I am on Windows 10 and have tried this with Unity 2019.2.13 and 2019.3.0 with the same result. Thanks in advance!

Here's that part of the build output that I mentioned:

stdout:
Building build.bc with EmscriptenToolChain
Output directory: C:\Users\CoreLabs\Unity Projects\2D Multiplayer Shooter\Temp\StagingArea\Data\Native
Cache directory: C:\Users\CoreLabs\Unity Projects\2D Multiplayer Shooter\Library\il2cpp_cache
il2cpp.exe didn't catch exception: Unity.IL2CPP.Building.BuilderFailedException: C:\Program Files\Unity\Hub\Editor\2019.3.0f6\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten_Win\python\2.7.5.3_64bit\python.exe: can't open file 'C:\Program Files\Emscripten\emscripten\1.29.0\emcc': [Errno 2] No such file or directory

 

Quick update: I completely uninstalled and reinstalled Unity onto a completely different drive inside my PC, but I'm still getting the same error. Also now my VC Code code completion is broken haha. What a day!

 

I was completely missing an Emscriptem folder in "Program Files". I fixed a similar issue by making the missing folders by hand in Program Files and copying the contents of "C:\Program Files\Unity\Hub\Editor\2019.4.7f1\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten" into that folder.

Although, I'm somewhat mystified how I got to a state where Unity has the files it needs packaged within itself, but tries to reference it from a folder that doesn't exist.

 

I just ran into something similar and am currently waiting for Unity to reinstall (I tried the wipe and start-over approach too). However my error message referenced a version of Emscripten that I used a few years ago, and I think that's a clue. I believe Unity Hub does not install Emscripten if it finds the system variables for an existing (or prior) installation.
I've renamed all the system variables (by adding _tmp onto their names so I can reverse later if needed) and I will confirm or refute this theory in about 15 minutes after Unity reinstalls, and I add the dev studio patches, and wait for the project to do whatever it is that takes so long the first time you load it, then wait 5-10 minutes for the webgl build.

 

Yes, that worked. Make sure you get all the system variables and all the path entries (there are 4-5 of each) from any old installation... then Unity will use the one it installed.