OK so here is my share of Console Build Errors after Upgrading to Unity 5.1
Looks like I’m going back to 5.0.2f1, thanks Unity for the tease of great WebGL features in Unity 5.1 that I can’t use due to WebGL Build issues! Arg… so annoying… 
I have no clue what any of this stuff means or how to fix it. Any help would be appreciated.
Can you post a full error output, or your editor.log file?
Here’s mine. I have the same error with 5.1f3.
2154074–142237–Editor.log.zip (38.2 KB)
Sure… here you go!
2154202–142251–Editor.zip (41.2 KB)
My experience (and some others) with this bug is described here:
I got it working on a fairly clean build only machine but on my main machine it does not work still and even a totally new project I encounter the bug. I did another search and it looks like running as admin may be a solution. Trying this now.
edit:I ran unity3d as administrator on the machine it doesn’t build on. No luck.
Webgl have many bugs ! and this is not one !
The log seems to indicate that emscripten failed to run it’s llvm-link executable. We’ve seen this before on some windows machines during 5.1 beta, which was then usually due to missing Visual Studio C++ redistributable dlls, and would get fixed by installing those. However, we believe that all issues related to that had been fixed, as we now bundle those dlls, so I’m not sure if this is related. I’ll ask our QA to do some testing and see if we can get a repro.
Specifically, when you try to execute llvm-link.exe in
PlaybackEngines/WebGLSupport/BuildTools/Emscripten_FastComp_Win/llvm-link.exe in your unity install on a command line, do you get any errors about missing dlls?
I’ll give it a try as soon as i’m back at my workstation. Thanks for the reply.
Please help with my eror . i posted on forum
Jonas, I’m on Mac. See my log please.
Nope… It just says something about Not enough positional command line arguments (See screenshot)
Edit: I tried downloading the Visual Studio dlls from here:
https://www.microsoft.com/en-us/download/details.aspx?id=40784
But no luck… same build error. 
I tried building with just a single cube in a scene, and still WebGL build failed but it provided a different build error:
WARNING root: emcc: link command line is very long, even with response file – use paths with no spaces
I moved my Unity Project Folder to the Root of C:\ did the test build again with Cube in Scene and now it works! 
I recall seeing a similar issue previously with WebGL Build providing a similar error in 5.0.2f1. My builds would not work until I moved them here “C:\Users\UserName\Unity Projects” that’s where I have been building from right now since 5.0.2f1. Now I need to move my project folder to root of C:\ in order to build? Geez… Please take not of this one jonas echterhoff. It’s very odd issue… builds fail because Unity does not like the path? 
I’ve seen the “use paths with no spaces” message before but I still have one machine that builds my project and one that doesn’t and they both have the project in the same path.
yeah, that one is just a warning. The actual error should be what you see when you scroll down, and I’d expect it to be the same. It is definitely a machine setup issue, we just have to figure out what it is.
But, maybe the message about “command lines being long” provides a clue here as to why it works for some people and not for others:
Can you check if moving the project to a shorter path name makes a difference? Ie, move your project folder directly to C: ?
I tried creating a new project directly in C:. This compiled just fine.
And the best part . . . My main project in its original location now compiles (on both machines now). This is a really strange bug. Good luck tracking it down.
I was thinking to try now moving the project from C:\ back to it’s orginal location and see if it builds now lol. Such an odd bug! I’m happy to at least be able to build and make use of the new Unity 5.1 WebGL features. Although would be nice keep my projects where I want them and not at the root of C:. 
So, just to confirm: Moving to C:\ did fix building for you?
