github/copilot-sdk · error · ArgumentException

CopilotClientOptions.WorkingDirectory is not supported with…

Error message

CopilotClientOptions.WorkingDirectory is not supported with RuntimeConnection.ForInProcess(): the in-process transport hosts the native runtime in the shared host process and spawns the worker without a working-directory parameter, so a per-client working directory cannot be honored in-process. Use a child-process transport, or set the process working directory before creating the client.

What it means

CopilotClient throws this ArgumentException when CopilotClientOptions.WorkingDirectory is set with RuntimeConnection.ForInProcess(). The in-process transport hosts the native runtime in the shared host process and spawns the worker without a working-directory parameter, so a per-client working directory cannot be honored. The library throws at construction rather than ignoring the value.

Solutions

  1. Set options.WorkingDirectory to null when using ForInProcess().
  2. Call Directory.SetCurrentDirectory(path) (or set the process working directory) before creating the client.
  3. Use RuntimeConnection.ForStdio() if a per-client working directory is required.

Example fix

// before
var options = new CopilotClientOptions { WorkingDirectory = @"C:\repos\app" };
var client = new CopilotClient(options, RuntimeConnection.ForInProcess());
// after
var options = new CopilotClientOptions();
Directory.SetCurrentDirectory(@"C:\repos\app");
var client = new CopilotClient(options, RuntimeConnection.ForInProcess());
Defensive patterns

Strategy: validation

Validate before calling

if (connection is InProcessRuntimeConnection && options.WorkingDirectory is not null)
    throw new InvalidOperationException("Use Directory.SetCurrentDirectory or ForStdio for a per-client working directory.");

Type guard

static bool AllowsOptionsWorkingDirectory(RuntimeConnection c) => c is not InProcessRuntimeConnection;

Try / catch

try { client = new CopilotClient(options, connection); }
catch (ArgumentException ex) when (ex.Message.Contains("WorkingDirectory")) { Directory.SetCurrentDirectory(options.WorkingDirectory); options.WorkingDirectory = null; client = new CopilotClient(options, connection); }

Prevention

When it happens

Trigger: new CopilotClient(options, RuntimeConnection.ForInProcess()) where options.WorkingDirectory is a non-null path. Checked by ValidateEnvironmentOptions during CopilotClient construction.

Common situations: Pointing the client at a project directory per workspace in a multi-workspace app; reusing options built for a stdio (child-process) transport after switching to in-process.

Understand the failure class

Background: Conflicting config options: "cannot be used together" — configuration validation errors across open-source libraries — this error's family across 162 libraries.

Related errors

AI-assisted analysis of github/copilot-sdk@cd8cf15dc3 (2026-09-09). Data as JSON: /api/errors/d9e10ec62c68d474. Report an issue: GitHub.

Appendix: source

Thrown at dotnet/src/Client.cs:253

                    "loads the native runtime into the shared host process, whose single environment block cannot carry " +
                    "per-client values. Set the variables on the host process environment instead.",
                    nameof(options));
            }

            if (options.Telemetry is not null)
            {
                throw new ArgumentException(
                    $"{nameof(CopilotClientOptions)}.{nameof(CopilotClientOptions.Telemetry)} is not supported with " +
                    $"{nameof(RuntimeConnection)}.{nameof(RuntimeConnection.ForInProcess)}(): telemetry configuration is " +
                    "lowered to environment variables read by native runtime code running in the shared host process, so " +
                    "per-client telemetry cannot be honored in-process. Configure telemetry via the host process " +
                    "environment, or use a child-process transport.",
                    nameof(options));
            }

            if (options.WorkingDirectory is not null)
            {
                throw new ArgumentException(
                    $"{nameof(CopilotClientOptions)}.{nameof(CopilotClientOptions.WorkingDirectory)} is not supported with " +
                    $"{nameof(RuntimeConnection)}.{nameof(RuntimeConnection.ForInProcess)}(): the in-process transport hosts " +
                    "the native runtime in the shared host process and spawns the worker without a working-directory " +
                    "parameter, so a per-client working directory cannot be honored in-process. Use a child-process " +
                    "transport, or set the process working directory before creating the client.",
                    nameof(options));
            }

            return;
        }

        if (connection is ChildProcessRuntimeConnection { Environment: not null } && options.Environment is not null)
        {
            throw new ArgumentException(
                $"Set environment variables via either {nameof(CopilotClientOptions)}.{nameof(CopilotClientOptions.Environment)} " +
                $"or {nameof(ChildProcessRuntimeConnection)}.{nameof(ChildProcessRuntimeConnection.Environment)}, not both. " +
                $"Prefer {nameof(ChildProcessRuntimeConnection)}.{nameof(ChildProcessRuntimeConnection.Environment)} for " +
                "child-process transports.",

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