stalwartlabs/stalwart · error · io::Error(Other)

journald not supported on non-Unix

Error message

journald not supported on non-Unix

What it means

On non-Unix targets the journald tracer's send_payload is a stub that always returns an io::Error of kind Other. Since real payload delivery only exists under #[cfg(unix)], any event sent on a non-Unix build fails with this message.

Source

Thrown at crates/common/src/telemetry/tracers/journald.rs:246

    ///
    /// See [Journal Fields](https://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html)
    /// and [journalctl](https://www.freedesktop.org/software/systemd/man/journalctl.html)
    /// for more information.
    ///
    /// Defaults to the file name of the executable of the current process, if any.
    pub fn with_syslog_identifier(mut self, identifier: String) -> Self {
        self.syslog_identifier = identifier;
        self
    }

    /// Returns the syslog identifier in use.
    pub fn syslog_identifier(&self) -> &str {
        &self.syslog_identifier
    }

    #[cfg(not(unix))]
    fn send_payload(&self, _opayload: &[u8]) -> io::Result<()> {
        Err(io::Error::new(
            io::ErrorKind::Other,
            "journald not supported on non-Unix",
        ))
    }

    #[cfg(unix)]
    fn send_payload(&self, payload: &[u8]) -> io::Result<usize> {
        self.socket
            .send_to(payload, JOURNALD_PATH)
            .or_else(|error| {
                if Some(libc::EMSGSIZE) == error.raw_os_error() {
                    self.send_large_payload(payload)
                } else {
                    Err(error)
                }
            })
    }

View on GitHub (pinned to e962003857)

Solutions

  1. Reconfigure logging to a supported sink on non-Unix platforms.
  2. Ensure the journald tracer is only enabled in Unix deployments.
  3. Handle the io::Result error from send_event and fall back to another tracer.

Example fix

// before
tracer.send_event(evt).ok();
// after
if cfg!(not(unix)) { file_tracer.send_event(evt) } else { tracer.send_event(evt) }
Defensive patterns

Strategy: fallback

Validate before calling

if cfg!(not(unix)) { use_file_tracer_instead(); }

Type guard

fn can_send_to_journald() -> bool { cfg!(unix) }

Try / catch

if tracer.send_event(event).is_err() {
    fallback_tracer.send_event(event);
}

Prevention

When it happens

Trigger: Calling send_payload (via send_event when emitting telemetry events) on a non-Unix build — every event dispatch returns this error.

Common situations: A binary compiled for Windows/macOS(non-unix target) still configured to log to journald; platform-gated config not applied at runtime.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

Related errors

AI-assisted analysis of stalwartlabs/stalwart@e962003857 (2026-09-06). Data as JSON: /api/errors/206c3aa616290f1b. Report an issue: GitHub.