Error when package for html5

Anyone can help me?

LogPlayLevel: mono: Setting Emscripten SDK
LogPlayLevel: mono:
LogPlayLevel: mono: ==============================================================================
LogPlayLevel: mono: Welcome to Emscripten!
LogPlayLevel: mono:
LogPlayLevel: mono: This is the first time any of the Emscripten tools has been run.
LogPlayLevel: mono:
LogPlayLevel: mono: A settings file has been copied to ~/.emscripten, at absolute path: /Users/Shared/UnrealEngine/4.12/Engine/Intermediate/Build/HTML5/.emscripten
LogPlayLevel: mono:
LogPlayLevel: mono: It contains our best guesses for the important paths, which are:
LogPlayLevel: mono:
LogPlayLevel: mono: LLVM_ROOT = /Users/Shared/UnrealEngine/4.12/Engine/Source/ThirdParty/HTML5/emsdk/Mac/clang/e1.35.0_64bit
LogPlayLevel: mono: NODE_JS = /Users/Shared/UnrealEngine/4.12/Engine/Source/ThirdParty/HTML5/emsdk/Mac/node/4.1.1_64bit/bin/node
LogPlayLevel: mono: EMSCRIPTEN_ROOT = /Users/Shared/UnrealEngine/4.12/Engine/Source/ThirdParty/HTML5/emsdk/emscripten/1.35.0
LogPlayLevel: mono:
LogPlayLevel: mono: Please edit the file if any of those are incorrect.
LogPlayLevel: mono:
LogPlayLevel: mono: This command will now exit. When you are done editing those paths, re-run it.
LogPlayLevel: mono: ==============================================================================
LogPlayLevel: mono:
LogPlayLevel: mono: Performing 1 actions (8 in parallel)
LogPlayLevel: mono: [1/1] python MyProject.js
LogPlayLevel: mono: INFO:root:e[32m(Emscripten: Running sanity checks)e[0m
LogPlayLevel: mono: INFO:root:e[32mClosure compiler (/Users/Shared/UnrealEngine/4.12/Engine/Source/ThirdParty/HTML5/emsdk/emscripten/1.35.0/third_party/closure-compiler/compiler.jar) does not exist, check the paths in /Users/Shared/UnrealEngine/4.12/Engine/Intermediate/Build/HTML5/.emscriptene[0m
LogPlayLevel: mono: INFO:root:e[32mclosure compiler will not be availablee[0m
LogPlayLevel: mono: error: Linking globals named ‘_Z14UELinkerFixupsv’: symbol multiply defined!
LogPlayLevel: mono: Traceback (most recent call last):
LogPlayLevel: mono: File “/Users/Shared/UnrealEngine/4.12/Engine/Source/ThirdParty/HTML5/emsdk/emscripten/1.35.0/emcc”, line 1309, in
LogPlayLevel: mono: final = shared.Building.llvm_opt(final, link_opts, DEFAULT_FINAL)
LogPlayLevel: mono: File “/Users/Shared/UnrealEngine/4.12/Engine/Source/ThirdParty/HTML5/emsdk/emscripten/1.35.0/tools/shared.py”, line 1465, in llvm_opt
LogPlayLevel: mono: assert os.path.exists(target), 'Failed to run llvm optimizations: ’ + output
LogPlayLevel: mono: AssertionError: Failed to run llvm optimizations:
LogPlayLevel: mono: ERROR: UBT ERROR: Failed to produce item: /Users/lyx/Documents/Unreal Projects/MyProject/Binaries/HTML5/MyProject.js
LogPlayLevel: mono: Total build time: 32.65 seconds
LogPlayLevel: CommandUtils.Run: Run: Took 32.842487s to run mono, ExitCode=5
LogPlayLevel: Program.Main: ERROR: AutomationTool terminated with exception: AutomationTool.AutomationException: Command failed (Result:5): /Users/Shared/UnrealEngine/4.12/Engine/Binaries/DotNET/UnrealBuildTool.exe MyProject HTML5 Development -Project="/Users/lyx/Documents/Unreal Projects/MyProject/MyProject.uproject" “/Users/lyx/Documents/Unreal Projects/M
yProject/MyProject.uproject” -remoteini="/Users/lyx/Documents/Unreal Projects/MyProject" -noxge -nocreatestub -NoHotReloadFromIDE -ignorejunk. See logfile for details: ‘UnrealBuildTool-2016.06.15-14.40.27.txt’
LogPlayLevel: at AutomationTool.CommandUtils.RunAndLog (System.String App, System.String CommandLine, System.String Logfile, Int32 MaxSuccessCode, System.String Input, ERunOptions Options, System.Collections.Generic.Dictionary2 EnvVars) [0x00000] in :0 LogPlayLevel: at AutomationTool.CommandUtils.RunAndLog (AutomationTool.CommandEnvironment Env, System.String App, System.String CommandLine, System.String LogName, Int32 MaxSuccessCode, System.String Input, ERunOptions Options, System.Collections.Generic.Dictionary2 EnvVars) [0x00000] in :0
LogPlayLevel: at AutomationTool.CommandUtils.RunUBT (AutomationTool.CommandEnvironment Env, System.String UBTExecutable, System.String CommandLine, System.String LogName, System.Collections.Generic.Dictionary2 EnvVars) [0x00000] in :0 LogPlayLevel: at AutomationTool.CommandUtils.RunUBT (AutomationTool.CommandEnvironment Env, System.String UBTExecutable, UnrealBuildTool.FileReference Project, System.String Target, System.String Platform, System.String Config, System.String AdditionalArgs, System.String LogName, System.Collections.Generic.Dictionary2 EnvVars) [0x00000] in :0
LogPlayLevel: at AutomationTool.UE4Build.BuildWithUBT (System.String TargetName, UnrealTargetPlatform TargetPlatform, System.String Config, UnrealBuildTool.FileReference UprojectPath, Boolean ForceMonolithic, Boolean ForceNonUnity, Boolean ForceDebugInfo, Boolean ForceFlushMac, Boolean DisableXGE, System.String InAddArgs, Boolean ForceUnity, System.Collect
ions.Generic.Dictionary2 EnvVars) [0x00000] in :0 LogPlayLevel: at AutomationTool.UE4Build.Build (AutomationTool.BuildAgenda Agenda, Nullable1 InDeleteBuildProducts, Boolean InUpdateVersionFiles, Boolean InForceNoXGE, Boolean InUseParallelExecutor, Boolean InForceNonUnity, Boolean InForceUnity, Boolean InShowProgress, System.Collections.Generic.Dictionary2 PlatformEnvVars, Nullable1 InChangelistNumberO
verride, System.Collections.Generic.Dictionary2 InTargetToManifest) [0x00000] in :0 LogPlayLevel: at Project.Build (AutomationTool.BuildCommand Command, AutomationTool.ProjectParams Params, Int32 WorkingCL, ProjectBuildTargets TargetMask) [0x00000] in :0 LogPlayLevel: at BuildCookRun.DoBuildCookRun (AutomationTool.ProjectParams Params) [0x00000] in :0 LogPlayLevel: at BuildCookRun.ExecuteBuild () [0x00000] in :0 LogPlayLevel: at AutomationTool.BuildCommand.Execute () [0x00000] in :0 LogPlayLevel: at AutomationTool.Automation.Execute (System.Collections.Generic.List1 CommandsToExecute, Tools.DotNETCommon.CaselessDictionary.CaselessDictionary1 Commands) [0x00000] in :0 LogPlayLevel: at AutomationTool.Automation.Process (System.String[] CommandLine) [0x00000] in :0 LogPlayLevel: at AutomationTool.Program.MainProc (System.Object Param) [0x00000] in :0 LogPlayLevel: at AutomationTool.InternalUtils.RunSingleInstance (System.Func2 Main, System.Object Param) [0x00000] in :0
LogPlayLevel: at AutomationTool.Program.Main () [0x00000] in :0
LogPlayLevel: Program.Main: AutomationTool exiting with ExitCode=5 (5)
LogPlayLevel: Domain_ProcessExit
LogPlayLevel: Completed Launch On Stage: Build Task, Time: 52.276195
LogPlayLevel: RunUAT ERROR: AutomationTool was unable to run successfully.
PackagingResults:Error: Error Launch failed! Unknown Error

Hi!

I created a project from a template FP and package to HTML5. All works for me.

You have installed Visual Studio 2015?

You must have Visual Studio to package, even if you are working with a blueprint project.