gofiber/fiber · error

failed to create directory

Error message

failed to create directory: %w

What it means

Response.Save attempts os.MkdirAll(dir, 0o750) when the target directory does not exist. This wraps a failure of that call: a parent component is a file (ENOTDIR), permission denied (EACCES), or read-only filesystem.

Solutions

1. Use a save directory known to be writable by the process (e.g. os.TempDir()).
2. Resolve the full path and ensure no ancestor is a regular file before calling Save.
3. Mount a writable volume at the save location in containerized deployments.

Example fix

// before
if err := resp.Save("/var/lock/downloads/out.bin"); err != nil { ... }

// after
dir := filepath.Join(os.TempDir(), "downloads")
_ = os.MkdirAll(dir, 0o750)
if err := resp.Save(filepath.Join(dir, "out.bin")); err != nil { ... }

if err := os.MkdirAll(dir, 0o750); err != nil {
    return fmt.Errorf("cannot use save dir %q: %w", dir, err)
}

When it happens

Trigger: The save path's parent doesn't exist and cannot be created; a parent in the chain is a regular file; the process cannot write to the location; mount is read-only.

Common situations: User-supplied download paths; containers with read-only volumes; chroot/jail missing a writable directory; path collision where an ancestor is a file.

Related errors

• failed to check directory
• failed to create file
• failed to write response body to file
• failed to write response body to writer
• open file error

AI-assisted analysis of gofiber/fiber@a105acad6c (2026-08-11). Data as JSON: /api/errors/6c4cb38364f76b0b. Report an issue: GitHub.

Appendix: source

Thrown at client/response.go:199

// Save writes the response body to a file or io.Writer.
// If a string path is provided, it creates directories if needed, then writes to a file.
// If an io.Writer is provided, it writes directly to it.
// When streaming is enabled, the body is read directly from the stream.
func (r *Response) Save(v any) error {
	switch p := v.(type) {
	case string:
		file := filepath.Clean(p)
		dir := filepath.Dir(file)

		// Create directory if it doesn't exist
		if _, err := os.Stat(dir); err != nil {
			if !errors.Is(err, fs.ErrNotExist) {
				return fmt.Errorf("failed to check directory: %w", err)
			}

			if err = os.MkdirAll(dir, 0o750); err != nil {
				return fmt.Errorf("failed to create directory: %w", err)
			}
		}

		// Create and write to file
		outFile, err := os.Create(file)
		if err != nil {
			return fmt.Errorf("failed to create file: %w", err)
		}
		defer func() { _ = outFile.Close() }() //nolint:errcheck // not needed

		// Use BodyStream() which handles both streaming and non-streaming cases
		if _, err = io.Copy(outFile, r.BodyStream()); err != nil {
			return fmt.Errorf("failed to write response body to file: %w", err)
		}

		return nil

	case io.Writer:

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