rustdesk/rustdesk · error

Failed to run the update exe with UAC, error: {:?}

Error message

Failed to run the update exe with UAC, error: {:?}

What it means

In `update_to()`, a `.exe` update package is launched elevated via `run_uac(file, "--update")`. If the UAC-elevated launch fails (returns false), the code bails reporting `std::io::Error::last_os_error()` — the last Win32 error from the spawn attempt, not a precise cause by itself.

Source

Thrown at src/platform/windows.rs:3886

    } else {
        log::info!("No custom txt found to stage for update.");
    }

    Ok(())
}

// Used for auto update and manual update in the main window.
pub fn update_to(file: &str) -> ResultType<()> {
    if file.ends_with(".exe") {
        let custom_client_staging_dir = get_custom_client_staging_dir();
        if crate::is_custom_client() {
            handle_custom_client_staging_dir_before_update(&custom_client_staging_dir)?;
        } else {
            // Clean up any residual staging directory from previous custom client
            allow_err!(remove_custom_client_staging_dir(&custom_client_staging_dir));
        }
        if !run_uac(file, "--update")? {
            bail!(
                "Failed to run the update exe with UAC, error: {:?}",
                std::io::Error::last_os_error()
            );
        }
    } else if file.ends_with(".msi") {
        if let Err(e) = update_me_msi(file, false) {
            bail!("Failed to run the update msi: {}", e);
        }
    } else {
        // unreachable!()
        bail!("Unsupported update file format: {}", file);
    }
    Ok(())
}

// Don't launch tray app when running with `\qn`.
// 1. Because `/qn` requires administrator permission and the tray app should be launched with user permission.
//   Or launching the main window from the tray app will cause the main window to be launched with administrator permission.

View on GitHub (pinned to 91c9fccbb0)

Solutions

1. Re-run the update and accept the UAC prompt
2. Check `std::io::Error::last_os_error()` value: ERROR_CANCELLED means user denial (expected, not fatal)
3. Verify the downloaded exe is intact, signed, and not quarantined by AV/SmartScreen
4. Ensure UAC is enabled and the user account can elevate

Example fix

// before
if !run_uac(file, "--update")? {
    bail!("Failed to run the update exe with UAC, error: {:?}", std::io::Error::last_os_error());
}
// after
if !run_uac(file, "--update")? {
    let e = std::io::Error::last_os_error();
    if e.raw_os_error() == Some(1223 /* ERROR_CANCELLED */) {
        log::info!("User cancelled UAC prompt; update aborted");
        return Ok(());
    }
    bail!("Failed to run the update exe with UAC, error: {e:?}");
}

// pre-check: package exists and account can elevate
if !std::path::Path::new(update_exe).is_file() { return; }
let admin = is_user_admin(); // e.g. from this crate
if !admin { log::info!("UAC prompt will appear"); }

match update_to(file) {
    Err(e) if e.to_string().contains("with UAC") => {
        let code = std::io::Error::last_os_error().raw_os_error();
        if code == Some(1223) { /* user cancelled: not fatal */ }
        else { log::error!("UAC launch failed: {e}"); }
    }
    Err(e) => return Err(e),
    Ok(()) => {}
}

When it happens

Trigger: `update_to()` called with a `.exe` path where `run_uac` returns false: user cancels the UAC prompt, UAC is disabled with elevation required, the exe is blocked (SmartScreen/AV), or ShellExecute-like spawn fails.

Common situations: User clicks 'No' on the UAC consent dialog; application published via a policy that blocks unsigned exe elevation; exe deleted/locked between download and launch.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

• {tip} failed with elevated exit code {exit_code}: {}
• Windows did not return an elevated process handle
• Cannot get parent of current exe file
• Can't get file name of {src_exe}
• Cannot get parent directory of current exe

AI-assisted analysis of rustdesk/rustdesk@91c9fccbb0 (2026-09-10). Data as JSON: /api/errors/9620b7ad22a6a10c. Report an issue: GitHub.