What causes "Pleases install pcap2socks's dependency" in netchx/netch?

Install Npcap (the URL the controller opens: github.com/zhxie/pcap2socks#dependencies) with the WinPcap-compatible DLL option.

netchx/netch · error · MessageException

Pleases install pcap2socks's dependency

Error message

Pleases install pcap2socks's dependency

What it means

Thrown by PcapController.OnStartFailed when the pcap2socks log file is empty (Length == 0), interpreted as pcap2socks having died before producing any output — the classic signature of a missing Npcap/WinPcap capture dependency. Before throwing, it spawns a task that opens the pcap2socks dependencies URL after a 1-second delay.

Source

Thrown at Netch/Controllers/PcapController.cs:94

    }

    protected override void OnStarted()
    {
        Global.MainForm.BeginInvoke(() => _form.Show());
    }

    protected override void OnStartFailed()
    {
        if (new FileInfo(LogPath).Length == 0)
        {
            Task.Run(() =>
                {
                    Thread.Sleep(1000);
                    Utils.Utils.Open("https://github.com/zhxie/pcap2socks#dependencies");
                })
                .Forget();

            throw new MessageException("Pleases install pcap2socks's dependency");
        }

        Utils.Utils.Open(LogPath);
    }
}

View on GitHub (pinned to 9d99eb1c5a)

Solutions

Install Npcap (the URL the controller opens: github.com/zhxie/pcap2socks#dependencies) with the WinPcap-compatible DLL option.
Restart Netch after installing Npcap.
Verify Npcap is present: look for 'NPCAP' in `getcap -D` or the installed programs list.
If you didn't mean to use pcap2socks, switch the mode away from ShareMode.

Defensive patterns

Strategy: validation

Validate before calling

// Detect the missing capture dependency before offering ShareMode.
bool npcapInstalled = Directory.GetFiles(Environment.SystemDirectory, "wpcap.dll").Any()
    || Directory.GetFiles(Environment.GetFolderPath(Environment.SpecialFolder.System), "Packet.dll").Any();
if (!npcapInstalled)
    throw new MessageException("pcap2socks requires Npcap to be installed.");

Try / catch

try { await pcapController.StartAsync(server, mode); }
catch (MessageException ex) when (ex.Message.Contains("pcap2socks's dependency"))
{
    // The controller already opened the dependencies URL; prompt the user to install Npcap and restart.
    PromptInstallNpcapAndRestart();
}

Prevention

Install Npcap with the WinPcap API-compatible option before first use of ShareMode.
Disable ShareMode in the UI when Npcap isn't detected.
Reinstall Npcap if the ShareMode suddenly starts failing after an OS reset.
Prefer TUN mode if you don't want a capture driver dependency.

When it happens

Trigger: pcap2socks started, immediately exited because no packet capture driver (Npcap) is installed, and wrote nothing to its log; the ShareMode (PcapController) was selected on a machine without Npcap.

Common situations: Fresh Windows install with Netch but no Npcap; Npcap uninstalled; Npcap installed without the 'WinPcap API-compatible Mode' option; user picked ShareMode by mistake.

Related errors

AI-assisted analysis of netchx/netch@9d99eb1c5a (2026-08-13). Data as JSON: /api/errors/8d1d5ab05bd29087. Report an issue: GitHub.