Using PortMappings in WSL.Container throws "incorrect parameter"

[hultqvist]

Windows Version

Microsoft Windows [Version 10.0.26200.8655]

WSL Version

2.9.3.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

Whatever runs WSLC

Distro Version

Whatever runs WSLC

Other Software

NuGet: Microsoft.WSL.Containers 2.9.3

Repro Steps

 var containerSettings = new ContainerSettings(ImageName)
 {
     Name = ContainerName,
     EnableAutoRemove = true,
     PortMappings = new List<ContainerPortMapping>()
     {
         new (windowsPort: 8080,
         containerPort: 8080,
         protocol: PortProtocol.TCP),
     },
 };
 container = session.CreateContainer(containerSettings);

The following does not throw any exception, though does not map ports either.

 var containerSettings = new ContainerSettings(ImageName)
 {
     Name = ContainerName,
     EnableAutoRemove = true,
 };
 container = session.CreateContainer(containerSettings);

Expected Behavior

Something like

wslc --session MySession run --rm -p 8080:8080 --name MyContainer MyImage

Actual Behavior

System.ArgumentException: 'The parameter is incorrect.

The parameter is incorrect.
'

Diagnostic Logs

No response

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[hultqvist]

Logs sent by email

[OneBlue]

@hultqvist: This is the root cause of the error:

Microsoft.Windows.Wslc	Error	07-03-2026 11:23:12.583	"code: 	
failurecount: 	3
file: 	C:\__w\1\s\src\windows\wslcsession\WSLCContainer.cpp
function: 	
hr: 	0x80070057
linenumber: 	195
message: 	Port mappings are not supported without networking
threadid: 	22648
type: 	0"	C:\__w\1\s\src\windows\wslcsession\WSLCContainer.cpp			53272	22648	2		00000000-0000-0000-0000-000000000000				"	"

It's looking like you're trying to map a port inside a session that doesn't have networking enabled.

@florelis: It doesn't look like we actually expose session networking settings at this level, is networking always disabled when creating a session via winrt ? That would explain this error

[florelis]

We have networking settings at the container level.
I think you need to add NetworkingMode = ContainerNetworkingMode.Bridged to the container settings.

[hultqvist]

Adding NetworkMode fixed it.

I wish the exception rather than stating "The parameter is incorrect"(which parameter?),
would state the same as the logfile "Port mappings are not supported without networking"
or even better: "PortMappings require NetworkingMode = ContainerNetworkingMode.Bridged"

Using the similar wslc.exe command does not require specifying network, their difference in defaults threw me off.