What causes "load tree failed: %s" in siyuan-note/siyuan?

Check the notebook is mounted and the .sy file exists on disk at the path reported in the block info

load tree failed: %s

Error message

load tree failed: %s

What it means

Third failure mode of buildUpdatedTaskListItemBlockDOM (kernel/api/block_op.go): the block was found in the index and is a list item, but filesys.LoadTree failed to load the .sy document file for block.Box/block.Path. The underlying filesystem error is appended to the prefix, so the message tells you whether it was a missing file, permission problem, or parse failure.

Source

Thrown at kernel/api/block_op.go:61

	if util.InvalidIDPattern(input.ID, ret) {
		return input, false
	}
	return input, true
}

func buildUpdatedTaskListItemBlockDOM(id, marker string, luteEngine *lute.Lute) (data string, err error) {
	block, err := model.GetBlock(id, nil)
	if err != nil {
		return "", errors.New("get block failed: " + err.Error())
	}

	if "NodeListItem" != block.Type {
		return "", errors.New("block is not a list item")
	}

	tree, err := filesys.LoadTree(block.Box, block.Path, luteEngine)
	if err != nil {
		return "", errors.New("load tree failed: " + err.Error())
	}

	li := treenode.GetNodeInTree(tree, id)
	if li == nil {
		return "", errors.New("block not found")
	}

	if 3 != li.ListData.Typ {
		return "", errors.New("block is not a task list item")
	}

	if 1 != len(marker) {
		return "", errors.New("task list item marker length should be 1")
	}

	liMarker := marker[0]
	if '[' == liMarker || ']' == liMarker {
		return "", errors.New("task list item marker can not be [ or ]")

View on GitHub (pinned to afa823b6b4)

Solutions

Check the notebook is mounted and the .sy file exists on disk at the path reported in the block info
Remount/reopen the notebook and retry the update
If the file is missing but content matters, recover from history (.siyuan/history or /api/history/) or the data repo
Rebuild the index so stale entries pointing at gone files are cleaned up; inspect the appended underlying error in the kernel log

Defensive patterns

Strategy: validation

Validate before calling

const info = await fetchPost('/api/block/getBlockInfo', { id });
const nb = await fetchGet('/api/notebook/lsNotebooks');
const mounted = nb.data.notebooks.some(n => n.id === info.data.box && !n.closed);
if (!mounted) throw new Error('notebook not mounted; open it before updating');
await fetchPost('/api/block/updateTaskListItemMarker', { id, marker });

Type guard

const isMountedNotebook = (boxId: string, notebooks: { id: string; closed: boolean }[]): boolean =>
  notebooks.some(n => n.id === boxId && !n.closed);

Try / catch

if (/^load tree failed:/.test(e.message)) {
  // underlying fs error: check .sy exists on disk, remount notebook, or reindex; retry after fix
}

Prevention

Do not close/unmount notebooks while automated block updates run
Let external tools write .sy files only through the kernel, never alongside it
On load failures, verify the file on disk before retrying blindly

When it happens

Trigger: The .sy file was deleted, moved, or renamed on disk while its index entry survived (unmounted notebook, external file manipulation, interrupted sync); the notebook containing the block is closed/unmounted between index read and tree load; the .sy file is corrupted and cannot be parsed; filesystem permission or disk errors.

Common situations: Sync tool rewrote the notebook directory mid-call; user closed the notebook in another window; .sy files edited by external scripts or merged badly; antivirus/locking software blocking reads on Windows.

Related errors

AI-assisted analysis of siyuan-note/siyuan@afa823b6b4 (2026-08-18). Data as JSON: /api/errors/362d24e6f5a4285a. Report an issue: GitHub.