Error when trying to build from the source code

Good day,

Before You read through the rest of the post, English isn’t my native language so please forgive me if some things that I type don’t make too much sense.

Recently I’ve downloaded source code from the github (4.3.0 branch). However, after following through all of the steps in the Readme.txt provided at the github repository, I’ve hit a wall when trying to build from the source code. Following errors popup in Visual Studio:

Error 1 error LNK1181: cannot open input file ‘zlib_64.lib’ C:\UnrealEngine\Engine\Intermediate\ProjectFiles\LINK UE4
Error 2 error : Failed to produce item: C:\UnrealEngine\Engine\Binaries\Win64\UnrealHeaderTool-Core.dll C:\UnrealEngine\Engine\Intermediate\ProjectFiles\ERROR UE4
Error 3 error MSB3073: The command “…\Build\BatchFiles\Build.bat UE4Editor Win64 Development” exited with code -1. C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.MakeFile.Targets 38 5 UE4

Upon further inspection, I’ve found that the UnrealHeaderTool-Core.dll doesn’t even exists in the required dependencies (links provided at the Epics github repository). I’m not even sure about other errors or if any others will show up.
I’ve browsed through the forums looking to see if there were similar problems, but I haven’t found anything concrete.

So if anyone has any ideas I would be grateful.



After quite a few trials and errors, I managed to find a solution, though not sure if it can actually be called that.

Anyway, it seems that some files got corrupt during the cloning of the repository, that’s why he couldn’t access zlib_64.lib file in the first place to build. And apparently my SSD isn’t too friendly with corrupt files, so I had issues every time I tried to clone the repository on it.

Basically I fixed the issue by cloning a repository on my HDD and building it from there, I’ll try to build it from SSD later on today, hoping that this will be the end of it.

I’m not sure if this will help anyone, but if they run across a similar issue, I hope that this will help them avoid couple of headaches.
Also if I missed a thread where this topic should be, please move it to the appropriate one.


The zlib libraries are not in the GitHub repository, they are distributed in one of the required dependencies zip files that you extract into your checkout of the engine source. UnrealHeaderTool is built as part of the generated UE4 solution, so the binary for that is not distributed with the engine source. Anyway, glad you got your problem sorted.

We have the same problem… I’m having the 3 errors you had before… did you redownload all the files ? what cause this problem ? anyone ?

Hi, yeah, after a while I just gave up on trying to figure out what was the cause and simply downloaded the entire source code from scratch. It did seem like some files were corrupt, however I never managed to figure out where\why\how was the cause.
I did try with later engines as well, and haven’t had any issues compiling. If you keep having the same issue as I did, most likely something was corrupt during the download and try downloading the source code again, it should solve the issue.

Good luck!

Hey WerdNaWerd,

Which engine version did you try downloading and do you get the same errors when trying to use other engine versions? As arhon mentioned there may have been an error during the download process that corrupted some files and deleting/redownloading the engine should help. Let us know if you’re still having any problems downloading/running the source code.