Cannot compile converting from 4.4 to 4.6

I am moving our project to 4.6 and I’m getting the following error when trying to build:

1>LogWindows : error : Windows GetLastError: The operation completed successfully. (0)
1>Error : Failed to generate code for UE4Editor - error code: CrashOrAssert (3)
1>  UnrealHeaderTool failed for target 'UE4Editor' (platform: Win64, module info:     C:\dev\UnrealEngineClean\Engine\Intermediate\Build\Win64\UE4Editor\DebugGame\UnrealHeaderTool.manifest).
1>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.MakeFile.Targets(38,5): error MSB3073: The command "..\..\Build\BatchFiles\Build.bat UE4Editor Win64 DebugGame" exited with code -1.
========== Build: 0 succeeded, 1 failed, 1 up-to-date, 0 skipped ==========

This happens after the initial ~34 actions for the core and instead seems to fail when moving on to the editor (full log here).

The error isn’t very helpful, almost looks like it is misinterpreting “The operation completed successfully” as an error.

I checked out 4.6 from Github. The only local changes appear to be the DLLs and such that are in the dependencies.

I saw it was crashing running the UHT with the following command line args:

UE4Editor "C:\dev\UnrealEngineClean\Engine\Intermediate\Build\Win64\UE4Editor\DebugGame\UnrealHeaderTool.manifest" -LogCmds="loginit warning, logexit warning, logdatabase error"

So I debugged that and got the following error:

ICU data directory was not discovered:

Those directories don’t exist, do I have to re-download the dependencies when upgrading from 4.4 to 4.6?

Closed, because of duplication: