spacedriveapp/spacedrive · error · anyhow::Error

Failed to send length: {}

Error message

Failed to send length: {}

What it means

send.write_all on the 4-byte big-endian length prefix failed at the very start of the request write. At that moment the QUIC connection or stream died: the peer reset the stream immediately, the connection was lost right after connect, or the local endpoint was stopped mid-send.

Source

Thrown at core/src/service/network/transports/sync.rs:266

			}

			new_conn
		};

		// Open bidirectional stream
		let (mut send, mut recv) = conn
			.open_bi()
			.await
			.map_err(|e| anyhow::anyhow!("Failed to open bidirectional stream: {}", e))?;

		// Serialize and send request
		let req_bytes = serde_json::to_vec(&request)
			.map_err(|e| anyhow::anyhow!("Failed to serialize sync request: {}", e))?;

		let len = req_bytes.len() as u32;
		send.write_all(&len.to_be_bytes())
			.await
			.map_err(|e| anyhow::anyhow!("Failed to send length: {}", e))?;
		send.write_all(&req_bytes)
			.await
			.map_err(|e| anyhow::anyhow!("Failed to send request: {}", e))?;

		// Properly close send stream
		send.finish()
			.map_err(|e| anyhow::anyhow!("Failed to finish stream: {}", e))?;

		debug!("Sync request sent, waiting for response...");

		// Read response with timeout
		let result = timeout(Duration::from_secs(60), async {
			let mut len_buf = [0u8; 4];
			recv.read_exact(&mut len_buf)
				.await
				.map_err(|e| anyhow::anyhow!("Failed to read response length: {}", e))?;
			let resp_len = u32::from_be_bytes(len_buf) as usize;

View on GitHub (pinned to 6dfeccf211)

Solutions

1. Evict the cached connection for this cache_key and retry the request once over a new connection
2. If it repeats for one specific peer, check that peer's logs for stream resets or panics in the sync handler
3. Make shutdown cancel in-flight sync sends so they fail with a cancellation instead of a write error

if let Err(e) = send.write_all(&len.to_be_bytes()).await {
    active_connections.write().await.remove(&cache_key);
    // retry the whole send once on a fresh connection, only if the request is idempotent
}

When it happens

Trigger: Peer accepts the connection then resets the sync stream (handler panic or protocol mismatch); connection lost in the window between connect() and the first write; daemon shutdown dropping the endpoint during the send.

Common situations: Flaky links, peers under memory pressure closing streams, shutdown races in tests.

Related errors

• Failed to send request: {}
• Failed to open bidirectional stream: {}
• Failed to send length: {}
• Failed to send request: {}
• Failed to read response length: {}

AI-assisted analysis of spacedriveapp/spacedrive@6dfeccf211 (2026-08-16). Data as JSON: /api/errors/e0f7b29807002bab. Report an issue: GitHub.