What causes "write data [%s] failed: %s" in siyuan-note/siyuan?

Free disk space and retry the write.

write data [%s] failed: %s

Error message

write data [%s] failed: %s

What it means

Returned by `writeTreeByWriteFile` when `filelock.WriteFile(filePath, data)` fails. The underlying error is wrapped into a descriptive message that includes the file path and the original error, then logged via `logging.LogErrorf` before being returned. This is the I/O failure path for persisting a `.sy` tree to disk.

Source

Thrown at kernel/filesys/tree.go:440

		}
	}

	if util.ExceedLargeFileWarningSize(len(data)) {
		msg := fmt.Sprintf(util.Langs[util.Lang][268], tree.Root.IALAttr("title")+" "+filepath.Base(filePath), util.LargeFileWarningSize)
		util.PushErrMsg(msg, 7000)
	}

	cache.SetTreeDataInBox(tree.ID, tree.Box, data)
	afterWriteTree(tree)
	size = uint64(len(data))
	return
}

func writeTreeByWriteFile(filePath string, data []byte) (err error) {
	if err = filelock.WriteFile(filePath, data); err != nil {
		msg := fmt.Sprintf("write data [%s] failed: %s", filePath, err)
		logging.LogErrorf("%s", msg)
		err = errors.New(msg)
		return
	}
	return
}

func prepareWriteTree(tree *parse.Tree) (data []byte, filePath string, err error) {
	luteEngine := util.NewLute() // 不关注用户的自定义解析渲染选项

	if nil == tree.Root.FirstChild {
		newP := treenode.NewParagraph("")
		tree.Root.AppendChild(newP)
		tree.Root.SetIALAttr("updated", util.TimeFromID(newP.ID))
		treenode.UpsertBlockTree(tree)
	}

	treenode.UpgradeSpec(tree)

	if _, err = ValidateBoxRelativePath(tree.Box, tree.Path); err != nil {

View on GitHub (pinned to 251596fc0d)

Solutions

Free disk space and retry the write.
Check filesystem permissions on `data/` and the target box directory.
Inspect the wrapped error in the log for the specific OS error (ENOENT, EACCES, etc.) and address it.
If a stale lock is suspected, ensure no other SiYuan kernel is running against the same workspace.

Defensive patterns

Strategy: try-catch

Validate before calling

// Pre-check writability when possible:
if err := os.MkdirAll(filepath.Dir(filePath), 0755); err != nil {
    return err
}

Try / catch

if err := filesys.WriteTree(tree); err != nil {
    if strings.Contains(err.Error(), "write data") {
        // surface the wrapped OS error to the user; offer retry/history restore
    }
    return err
}

Prevention

Monitor free disk space on the workspace volume.
Ensure the data dir and box dirs are writable by the kernel process.
Avoid running two kernels against one workspace to prevent file-lock contention.

When it happens

Trigger: Disk full, permission denied, read-only filesystem, file locked by another process, or the parent directory removed mid-write. Any error from `filelock.WriteFile` is funneled into this message.

Common situations: Synchronizing to a full disk; antivirus/filelock contention on Windows; running on a read-only mount; path to a directory that no longer exists after a move.

Related errors

AI-assisted analysis of siyuan-note/siyuan@251596fc0d (2026-08-12). Data as JSON: /api/errors/034aab3e306ae38d. Report an issue: GitHub.