What causes "Failed to empty clipboard files for conn_id {}" in rustdesk/rustdesk?

Guard against duplicate cleanup — skip if the connection was already marked cleaned.

Failed to empty clipboard files for conn_id {}

Error message

Failed to empty clipboard files for conn_id {}

What it means

After asking the server-side file clipboard context to empty the files for a connection, it reports empty_clipboard(conn_id) == false, meaning the per-connection file clipboard data could not be cleared for that conn_id. The library bails so the caller knows cleanup did not take effect.

Source

Thrown at src/clipboard.rs:212

            }
        }
    }
    #[allow(unused_mut)]
    if let Some(mut ctx) = ctx.as_mut() {
        #[cfg(target_os = "linux")]
        {
            use clipboard::platform::unix;
            if unix::fuse::empty_local_files(_side == ClipboardSide::Client, _conn_id) {
                ctx.try_empty_clipboard_files(_side);
            }
        }
        #[cfg(target_os = "macos")]
        {
            ctx.try_empty_clipboard_files(_side);
            // No need to make sure the context is enabled.
            clipboard::ContextSend::proc(|context| -> ResultType<()> {
                if !context.empty_clipboard(_conn_id)? {
                    bail!("Failed to empty clipboard files for conn_id {}", _conn_id);
                }
                Ok(())
            })?;
        }
    }
    Ok(())
}

#[cfg(target_os = "windows")]
pub fn try_empty_clipboard_files(side: ClipboardSide, conn_id: i32) {
    log::debug!("try to empty {} cliprdr for conn_id {}", side, conn_id);
    let _ = clipboard::ContextSend::proc(|context| -> ResultType<()> {
        context.empty_clipboard(conn_id)?;
        Ok(())
    });
}

#[cfg(target_os = "windows")]

View on GitHub (pinned to 91c9fccbb0)

Solutions

Guard against duplicate cleanup — skip if the connection was already marked cleaned.
Treat a false return during disconnect as non-fatal: log a warning instead of propagating the error.
Verify conn_id passed in matches the active connection (no stale id from a closed session).

Example fix

// before
 try_empty_clipboard_files(conn_id, side)?;
// after: cleanup is best-effort
 if let Err(e) = try_empty_clipboard_files(conn_id, side) {
     log::warn!("empty clipboard files: {:?}", e);
 }

Defensive patterns

Strategy: try-catch

Try / catch

if let Err(e) = try_empty_clipboard_files(conn_id, side) {
    log::warn!("empty clipboard files for conn {}: {}", conn_id, e);
}

Prevention

Track which connections have already been cleaned to avoid double-empty
Validate conn_id is still active before cleanup
Treat teardown-time clipboard errors as warnings, not failures

When it happens

Trigger: try_empty_clipboard_files for a _conn_id whose file clipboard entry no longer exists or was already cleared — ContextSend::proc finds a live context but empty_clipboard returns false for the given connection id (double cleanup, unknown conn_id, or state mismatch).

Common situations: Calling empty twice for the same connection (both disconnect paths racing); conn_id already invalid because the peer disconnected concurrently; macOS server-side file clipboard state removed by another path before this call.

Related errors

AI-assisted analysis of rustdesk/rustdesk@91c9fccbb0 (2026-09-10). Data as JSON: /api/errors/90324b689b1b2c74. Report an issue: GitHub.