herdrdev/herdr · error

failed to spawn herdr server: {err}

Error message

failed to spawn herdr server: {err}

What it means

After resolving the executable path, spawn_server_daemon failed to launch the detached server process via the platform-specific launch_server_daemon_command. The OS spawn error is wrapped with a descriptive message. This is a process-spawn failure, not a server logic failure.

Source

Thrown at src/server/autodetect.rs:203

///   socket overrides, etc.), except inherited socket overrides are cleared when
///   this CLI invocation explicitly selected a session.
///
/// Returns the PID of the spawned server process.
pub fn spawn_server_daemon() -> io::Result<u32> {
    let exe = std::env::current_exe().map_err(|err| {
        io::Error::new(
            err.kind(),
            format!("failed to determine herdr executable path: {err}"),
        )
    })?;

    info!(exe = %exe.display(), "spawning server daemon");

    let mut command = build_server_daemon_command(exe);

    let pid =
        crate::platform::launch_server_daemon_command(&mut command).map_err(|err: io::Error| {
            io::Error::new(err.kind(), format!("failed to spawn herdr server: {err}"))
        })?;
    info!(pid, "server daemon spawned");

    Ok(pid)
}

fn build_server_daemon_command(exe: PathBuf) -> Command {
    let mut command = Command::new(&exe);
    command
        .arg("server")
        // Redirect stdio to /dev/null
        .stdin(std::process::Stdio::null())
        .stdout(std::process::Stdio::null())
        .stderr(std::process::Stdio::null());
    crate::platform::detach_server_daemon_command(&mut command);

    match std::env::current_dir() {
        Ok(cwd) => {

View on GitHub (pinned to f457cff4f2)

Solutions

1. Check errno in the message (PermissionDenied vs WouldBlock etc.) and fix accordingly
2. Verify the herdr binary is executable and its path is intact
3. Check system resource limits (ulimit -u, memory) if EAGAIN
4. Review security policy denials in system logs

use std::os::unix::fs::PermissionsExt;
assert!(std::env::current_exe().map(|p| p.metadata().map(|m| m.permissions().mode() & 0o111 != 0)).unwrap_or(false));

Err(e) if e.kind() == io::ErrorKind::WouldBlock => retry spawn after short delay

When it happens

Trigger: Platform launch failing: executable not executable, fork/exec permission denied, resource limits (EAGAIN), SELinux/AppArmor denial, or bad environment inherited by the spawn.

Common situations: Binary permissions broken after manual copy, system out of processes/memory, security policy blocking daemonization, or cross-platform spawn helper incompatibility.

Related errors

• failed to start ssh bridge: {err}
• failed to create private herdr ssh config directory
• failed to create private herdr ssh config directory
• failed to create private herdr ssh config directory
• ssh bootstrap stdin missing

AI-assisted analysis of herdrdev/herdr@f457cff4f2 (2026-08-28). Data as JSON: /api/errors/7d30121af5c4e127. Report an issue: GitHub.