moonD4rk/HackBrowserData · error

close %s: %w

Error message

close %s: %w

What it means

writeFile registers a deferred f.Close() and promotes its error (only if no earlier error occurred) via fmt.Errorf("close %s: %w", ...). This reports that closing the output file failed, typically meaning buffered data was never flushed to disk and the result file may be empty or incomplete.

Source

Thrown at output/output.go:154

	// cookie-editor skipping non-cookie data), don't create the file.
	var buf bytes.Buffer
	if err := o.formatter.format(&buf, rows); err != nil {
		return fmt.Errorf("format %s: %w", category, err)
	}
	if buf.Len() == 0 {
		return nil
	}

	filename := fmt.Sprintf("%s.%s", category, o.formatter.ext())
	path := filepath.Join(o.dir, filename)

	f, err := os.OpenFile(filepath.Clean(path), os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o600)
	if err != nil {
		return fmt.Errorf("create %s: %w", filename, err)
	}
	defer func() {
		if cerr := f.Close(); cerr != nil && err == nil {
			err = fmt.Errorf("close %s: %w", filename, cerr)
		}
	}()

	if strings.HasSuffix(path, ".csv") {
		if _, err := f.Write(utf8BOM); err != nil {
			return fmt.Errorf("write BOM: %w", err)
		}
	}

	if _, err := f.Write(buf.Bytes()); err != nil {
		return fmt.Errorf("write %s: %w", filename, err)
	}
	return nil
}

View on GitHub (pinned to 0503d04d7a)

Solutions

1. Check free disk space on the output volume and retry with adequate space.
2. Write to a local disk instead of a network/removable drive.
3. Exclude the output directory from AV/sync tools that may hold or interfere with the handle.
4. Treat the written file as unreliable: delete and regenerate after fixing the environment.

Example fix

// before: ignoring close errors leaves truncated files
f.Close()
// after
if cerr := f.Close(); cerr != nil && err == nil {
	err = fmt.Errorf("close %s: %w", filename, cerr)
}

// before writing, ensure adequate space:
if st, err := diskUsage(outputDir); err == nil && st.Free < minRequired { return errors.New("insufficient disk space") }

if err := w.Write(); err != nil {
	if strings.Contains(err.Error(), "close ") {
		// output unreliable: delete partial files and retry after freeing space
	}
}

When it happens

Trigger: The deferred f.Close() returned a non-nil error: disk became full (close flushes OS buffers), the file handle was invalidated (filesystem unmounted, network drive dropped), or on Windows an underlying lock/error surfaced at close time.

Common situations: Disk filling up mid-write so Close cannot flush; writing to a network share or removable drive that disconnects; file watched/locked by AV or sync clients (OneDrive/Dropbox) interfering at close.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• create output dir: %w
• create %s: %w
• write BOM: %w
• create temp dir: %w
• copy: %w

AI-assisted analysis of moonD4rk/HackBrowserData@0503d04d7a (2026-09-06). Data as JSON: /api/errors/da539e6068cd8dca. Report an issue: GitHub.