UE4.27 — Clean Blueprint project fails to package when OnlineSubsystemSteam is enabled: LNK2011 precompiled object not linked

Summary

Engine Version

Unreal Engine 4.27

Platform

Windows 10/11 64-bit

Project Type

Blueprint / Third Person template

Severity

Major

Summary

I am experiencing a packaging/linker failure in Unreal Engine 4.27 when the OnlineSubsystemSteam plugin is enabled.

The issue reproduces in a completely new UE4.27 project, without my own gameplay code or third-party plugins.

The same project packages successfully when OnlineSubsystemSteam is disabled.

This appears to isolate the problem to the UE4.27 OnlineSubsystemSteam build/link process rather than the project content.

Steps to Reproduce
Install Unreal Engine 4.27.
Create a new Third Person Blueprint project.
Target Windows 64-bit.
Do not add any third-party plugins or custom C++ code.
Enable:
{
“Name”: “OnlineSubsystem”,
“Enabled”: true
},
{
“Name”: “OnlineSubsystemUtils”,
“Enabled”: true
},
{
“Name”: “OnlineSubsystemSteam”,
“Enabled”: true
}
Package the project for Windows 64-bit.
Allow Unreal AutomationTool to build the project.
Actual Result

Packaging fails during the UnrealBuildTool linking stage.

The relevant error is:

Module.OnlineSubsystemSteam.cpp.obj : error LNK2011:
precompiled object not linked in; image may not run

This is followed by:

Steam_Test2.exe : fatal error LNK1120: 1 unresolved externals

and:

UnrealBuildTool failed. See log for more details.
AutomationTool exiting with ExitCode=6
BUILD FAILED

What Type of Bug are you experiencing?

Platform Other

Steps to Reproduce

Engine Version

Unreal Engine 4.27

Platform

Windows 10/11 64-bit

Project Type

Blueprint / Third Person template

Severity

Major

Summary

I am experiencing a packaging/linker failure in Unreal Engine 4.27 when the OnlineSubsystemSteam plugin is enabled.

The issue reproduces in a completely new UE4.27 project, without my own gameplay code or third-party plugins.

The same project packages successfully when OnlineSubsystemSteam is disabled.

This appears to isolate the problem to the UE4.27 OnlineSubsystemSteam build/link process rather than the project content.

Steps to Reproduce
Install Unreal Engine 4.27.
Create a new Third Person Blueprint project.
Target Windows 64-bit.
Do not add any third-party plugins or custom C++ code.
Enable:
{
“Name”: “OnlineSubsystem”,
“Enabled”: true
},
{
“Name”: “OnlineSubsystemUtils”,
“Enabled”: true
},
{
“Name”: “OnlineSubsystemSteam”,
“Enabled”: true
}
Package the project for Windows 64-bit.
Allow Unreal AutomationTool to build the project.
Actual Result

Packaging fails during the UnrealBuildTool linking stage.

The relevant error is:

Module.OnlineSubsystemSteam.cpp.obj : error LNK2011:
precompiled object not linked in; image may not run

This is followed by:

Steam_Test2.exe : fatal error LNK1120: 1 unresolved externals

and:

UnrealBuildTool failed. See log for more details.
AutomationTool exiting with ExitCode=6
BUILD FAILED

Expected Result

Actual Result

Packaging fails during the UnrealBuildTool linking stage.

The relevant error is:

Module.OnlineSubsystemSteam.cpp.obj : error LNK2011:
precompiled object not linked in; image may not run

This is followed by:

Steam_Test2.exe : fatal error LNK1120: 1 unresolved externals

and:

UnrealBuildTool failed. See log for more details.
AutomationTool exiting with ExitCode=6
BUILD FAILED

Observed Result

Actual Result

Packaging fails during the UnrealBuildTool linking stage.

The relevant error is:

Module.OnlineSubsystemSteam.cpp.obj : error LNK2011:
precompiled object not linked in; image may not run

This is followed by:

Steam_Test2.exe : fatal error LNK1120: 1 unresolved externals

and:

UnrealBuildTool failed. See log for more details.
AutomationTool exiting with ExitCode=6
BUILD FAILED

Affects Versions

4.27

Platform(s)

Windows

Video

Actual Result

The project fails during linking because:

Module.OnlineSubsystemSteam.cpp.obj

UBT-MyProject-Win64-Development.txt (29.3 KB)