zed-industries/zed · error · anyhow::Error

RmStartSession failed: {err:?}

Error message

RmStartSession failed: {err:?}

What it means

The Windows auto-updater uses the Restart Manager API to ask processes holding handles to Zed's files to release them. `RmStartSession` creates the RM session; if it returns an error HRESULT the whole handle-release step (and thus the update) is aborted with this message. This is a Win32/Restart Manager failure, not a Zed-logic failure.

Source

Thrown at crates/auto_update_helper/src/updater.rs:302

        app_dir.join("bin\\zed"),
        app_dir.join("conpty.dll"),
    ];

    log::info!("Attempting to release file handles using Restart Manager...");

    let mut session: u32 = 0;
    let mut session_key = [0u16; CCH_RM_SESSION_KEY as usize + 1];

    // Start a Restart Manager session
    let err = unsafe {
        RmStartSession(
            &mut session,
            Some(0),
            PWSTR::from_raw(session_key.as_mut_ptr()),
        )
    };
    if err.is_err() {
        anyhow::bail!("RmStartSession failed: {err:?}");
    }

    // Ensure we end the session when done
    let _session_guard = scopeguard::guard(session, |s| {
        let _ = unsafe { RmEndSession(s) };
    });

    // Convert paths to wide strings for Windows API
    let wide_paths: Vec<Vec<u16>> = files_to_release
        .iter()
        .filter(|p| p.exists())
        .map(|p| {
            OsStr::new(p)
                .encode_wide()
                .chain(std::iter::once(0))
                .collect()
        })
        .collect();

View on GitHub (pinned to f4178619ac)

Solutions

1. Verify required services are running: `sc query RpcSs` and check Event Viewer for Restart Manager errors; reboot to reset service state.
2. Run the updater with normal privileges and confirm the user can create sessions; try again after closing other applications.
3. If it persists, download the full installer and update manually — it replaces files without the RM path.
4. Report the HRESULT text from the log line to identify the specific Win32 error.

// Handle-release is an optimization; failing it should not abort the whole update
match release_file_handles(&files) {
    Ok(()) => {}
    Err(err) => log::warn!("restart manager unavailable ({err:#}); continuing without handle release"),
}
// proceed with the update

When it happens

Trigger: `RmStartSession(&mut session, Some(0), ...)` returns a failing HRESULT: RPC service unavailable, Restart Manager cannot allocate a session key, system resource exhaustion, or a stripped-down Windows where the service is disabled.

Common situations: Broken RPC/Windows services on the machine, Group Policy or security software blocking Restart Manager, very locked-down Windows installs, memory pressure preventing session creation.

Related errors

• RmRegisterResources failed: {err:?}
• RmShutdown failed: {:?}
• Delete operations cannot be rolled back, file: {}
• Autoupdate failed, nothing to rollback
• Job rollback failed, the app might be left in an inconsisten

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/3469ef70cd60b859. Report an issue: GitHub.