spacedriveapp/spacedrive · error

Arena index mismatch: expected {}, got {}

Error message

Arena index mismatch: expected {}, got {}

What it means

While deserializing an ephemeral index snapshot, each serialized node is re-inserted into a fresh NodeArena and the returned index is compared against the index the node had when serialized. A mismatch means the arena's allocation order changed between serialize and load: the snapshot is corrupt, was written by a different arena implementation, or the intern/parent layout shifted. The snapshot cannot be trusted for path resolution.

Source

Thrown at core/src/ops/indexing/ephemeral/snapshot.rs:222

		for &id in ids {
			registry.insert(interned, id);
		}
	}

	// Rebuild arena (convert SerializableFileNode back to FileNode)
	let mut arena = super::NodeArena::new()?;
	for (expected_idx, serializable_node) in snapshot.arena_entries {
		// Intern the name and create NameRef
		let interned_name = cache.intern(&serializable_node.name);
		let name_ref = super::types::NameRef::new(interned_name, serializable_node.parent);

		// Reconstruct FileNode
		let mut file_node = super::types::FileNode::new(name_ref, serializable_node.meta);
		file_node.children = serializable_node.children;

		let actual_idx = arena.insert(file_node)?;
		if actual_idx.as_usize() != expected_idx {
			anyhow::bail!(
				"Arena index mismatch: expected {}, got {}",
				expected_idx,
				actual_idx.as_usize()
			);
		}
	}

	// Reconstruct index using constructor
	let index = super::EphemeralIndex::from_snapshot_parts(
		arena,
		cache,
		registry,
		snapshot.path_index,
		snapshot.entry_uuids,
		snapshot.content_kinds,
		snapshot.stats,
	);

View on GitHub (pinned to 6dfeccf211)

Solutions

1. Delete the ephemeral snapshot cache so it is rebuilt from a fresh scan (ephemeral data is rebuildable by design)
2. Bump and check a snapshot format version so mismatches are detected explicitly instead of via index comparison
3. Write snapshots atomically (temp file + rename) so torn files never appear

// Check the snapshot format version before deserializing
if snapshot.format_version != EXPECTED_SNAPSHOT_VERSION {
    // stale/incompatible snapshot: delete and rebuild instead of loading
    std::fs::remove_file(&snapshot_path)?;
}

match load_snapshot(&path).await {
    Ok(index) => index,
    Err(e) if e.to_string().contains("Arena index mismatch") => {
        // ephemeral data is rebuildable: discard and rescan
        let _ = std::fs::remove_file(&path);
        rebuild_ephemeral_index_from_scan().await?
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Loading a snapshot written by an older/newer build whose NodeArena insert logic or node ordering differs; truncated or partially-written snapshot file; snapshot written while concurrent inserts mutated the arena.

Common situations: Daemon binary upgraded across a snapshot-format change; crash during snapshot write leaving a torn file; two processes sharing one snapshot path.

Related errors

• Failed to add entry to ephemeral index: {}
• EphemeralEventHandler not connected to FsWatcherService
• Non-local address not supported for indexing yet: {}
• Non-local path not supported yet
• Failed to parse response: {}

AI-assisted analysis of spacedriveapp/spacedrive@6dfeccf211 (2026-08-16). Data as JSON: /api/errors/d2948d94942b8673. Report an issue: GitHub.