Cannot execute c1xx.dll - build/compile issue with UE5.5

Development Programming & Scripting C++
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1

Top of the day to you all

I currently can’t build any ue5.5 c++ projects in visual studio (or rider) and get a D8027 error or ‘cannot execute c1xx.dll’

  • this effects VS and Rider and I don’t have this problem with ue5.4 c++ projects
  • I’ve even reinstalled VS to cleanup my tooling and its not fixing the issue…
  • I’ve tried adding to build.cs files bLegacyPublicIncludePaths = false;

There is not alot of info out there so any tips/thoughts would be greatly appreciated!

J

2

We have the same issues here, with any UE5 build above 5.5.

We’ve tried 5.5 and 5.6 now and are still getting these errors on compile.
We also use Rider and Visual C, but have tried without Rider, but still get the same error.

Any help to get around this and we’d be super grateful!

3

I was finally able to get a solution to this issue! I will post the solution that I had received from the Developer Assistant Chat Bot on Unreal Engine’s website. Not sure if you had a similar issue, since this error appeared after it tried to compile SharedPCH.UnrealEd.Project.ValApi.Cpp20.cpp. Chat bot response below:

Fix for Unreal Engine 5.5.4 Build Error D8027 Related to c1xx.dll Execution Failure

Problem:
During compilation, error D8027: cannot execute 'c1xx.dll' occurs, e.g., when building SharedPCH like SharedPCH.UnrealEd.Project.ValApi.Cpp20.cpp. This indicates MSVC compiler front-end DLL execution failure.

Solution Steps:

  1. Repair Visual Studio 2022 Toolchain:
    • Run Visual Studio Installer and repair VS, including “Desktop development with C++” and Windows SDK.
  2. Check for Antivirus/Permissions:

    • Ensure no antivirus or security software is blocking or quarantining c1xx.dll or cl.exe.

    • Run VS and Unreal Editor as Administrator.

    • Verify file permissions allow execution.

  3. Test Compiler Manually:

    • Open “Developer Command Prompt for VS 2022”.

    • Run the following:

"C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.38.33130\bin\Hostx64\x64\cl.exe"
  • Confirm no errors occur.

  1. Clean and Regenerate UE Project:

    • Delete Binaries/, Intermediate/, .vs/, and Saved/ folders.

    • Delete solution files.

    • Run GenerateProjectFiles.bat.

    • Rebuild in Visual Studio.

  2. Disable Unreal Build Accelerator (UBA):

    • Temporarily disable UBA in UE settings to prevent build execution issues.

      Edit: You can do this by navigating to AppData\Roaming\Unreal Engine\UnrealBuildTool\BuildConfiguration.xml and changing the file so that it looks something like this:

<?xml version="1.0" encoding="utf-8" ?>
<Configuration xmlns="https://www.unrealengine.com/BuildConfiguration">
	<BuildConfiguration>
		<bAllowUBAExecutor>false</bAllowUBAExecutor>
		<bAllowUBALocalExecutor>false</bAllowUBALocalExecutor>
	</BuildConfiguration>
</Configuration>
  1. Check Environment Variables and PATH:
    • Use a fresh Developer Command Prompt to build ensuring proper MSVC environment.

After these steps, the D8027 error caused by c1xx.dll execution is eliminated, allowing successful compilation.

1 Like
4

Thank you, turns out disabling the Unreal Build Accelerator fixes our error, but we’re going to go turn on verbose logging, and see if we can find what exactly is stopping it running.

Thanks for your pointers though, we wouldn’t have figured out it was the build accelerator!