ElectronNET/Electron.NET · error · ArgumentException

Unable to find process with ID

Error message

Unable to find process with ID {this.pid}

What it means

ElectronProcessPassive.StartCore attaches to an already-running Electron process by PID using Process.GetProcessById. .NET's GetProcessById throws ArgumentException when no process with that ID exists; the subsequent null check with this custom message is the library's guard for a missing process.

Solutions

1. Verify the target process with the given PID is actually running before starting (Process.GetProcesses / ps)
2. Re-launch the Electron host and use its fresh PID
3. Check for PID namespace issues when running in containers/WSL
4. Confirm the PID is not from a previous, terminated run

Example fix

// before
var proc = Process.GetProcessById(pid); // ArgumentException if gone
// after
if (!Process.GetProcesses().Any(p => p.Id == pid))
    throw new InvalidOperationException($"Process {pid} is not running");
var proc = Process.GetProcessById(pid);

if (!Process.GetProcesses().Any(p => p.Id == pid))
    throw new InvalidOperationException($"Electron host process {pid} is not running");

bool ProcessExists(int pid) => Process.GetProcesses().Any(p => p.Id == pid);

try
{
    await electronProcess.StartAsync();
}
catch (ArgumentException ex)
{
    logger.LogWarning(ex, "Host process {Pid} no longer exists — relaunching", pid);
    await relaunchHostAsync();
}

When it happens

Trigger: Starting the passive Electron process lifecycle with a PID that has already exited, a PID from a different OS namespace (e.g. container/host mismatch), or a stale/incorrect PID value.

Common situations: Attaching to an Electron host that crashed or was closed before the .NET side started; passing a PID captured long before use; WSL/container PID isolation hiding the host process.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

• Argument must be greater then 0

AI-assisted analysis of ElectronNET/Electron.NET@87cc6f98b6 (2026-09-14). Data as JSON: /api/errors/25523b2264b8af3d. Report an issue: GitHub.

Appendix: source

Thrown at src/ElectronNET.API/Runtime/Services/ElectronProcess/ElectronProcessPassive.cs:31

    internal class ElectronProcessPassive : ElectronProcessBase
    {
        private readonly int pid;
        private Process process;

        /// <summary>Initializes a new instance of the <see cref="ElectronProcessPassive"/> class.</summary>
        /// <param name="pid"></param>
        public ElectronProcessPassive(int pid)
        {
            this.pid = pid;
        }

        protected override Task StartCore()
        {
            this.process = Process.GetProcessById(this.pid);

            if (this.process == null)
            {
                throw new ArgumentException($"Unable to find process with ID {this.pid}");
            }

            this.process.Exited += this.Process_Exited1;

            Task.Run(() => this.TransitionState(LifetimeState.Ready));

            return Task.CompletedTask;
        }

        private void Process_Exited1(object sender, EventArgs e)
        {
            this.TransitionState(LifetimeState.Stopped);
        }

        protected override Task StopCore()
        {
            // Not sure about this:
            ////this.process.Kill(true);

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