anomalyco/sst · error

failed to open file for hashing: %w

Error message

failed to open file for hashing: %w

What it means

hashFileContents opens a file to compute its SHA256 and wraps os.Open failures with this message. The library throws it from copySyncedDependencies, which hashes files to detect changes for dev-mode sync. It means the file that the dependency list referenced could not be opened for reading at hash time.

Source

Thrown at pkg/runtime/python/python.go:458

		if skip(relPath, info) {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}
		dstPath := filepath.Join(dst, relPath)
		if info.IsDir() {
			return os.MkdirAll(dstPath, info.Mode())
		}
		return copyFile(p, dstPath)
	})
}

// hashFileContents computes a SHA256 hash of a file's contents.
func hashFileContents(filePath string) (string, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return "", fmt.Errorf("failed to open file for hashing: %w", err)
	}
	defer file.Close()

	hasher := sha256.New()
	if _, err := io.Copy(hasher, file); err != nil {
		return "", fmt.Errorf("failed to hash file: %w", err)
	}

	return hex.EncodeToString(hasher.Sum(nil)), nil
}

// hasWorkspaceLayoutPatterns checks for package/src/package patterns that need flattening.
// Scans up to one level below projectRoot to cover both single-package and monorepo layouts.
func (r *PythonRuntime) hasWorkspaceLayoutPatterns(projectRoot string) bool {
	var scan func(dir string, depth int) bool
	scan = func(dir string, depth int) bool {
		entries, err := os.ReadDir(dir)
		if err != nil {

View on GitHub (pinned to a0bd20f762)

Solutions

1. Verify the file exists at the hashed path (ls / stat) and recreate it if it was deleted
2. Restart `sst dev` so the dependency list and hashes are recomputed
3. Check file permissions/ownership of the dependency files
4. If files are frequently mid-write, ignore ENOENT for files that vanished during sync

func fileExists(path string) bool {
	fi, err := os.Stat(path)
	return err == nil && fi.Mode().IsRegular()
}
// before syncing: ensure every dependency path hashes-exists
// if !fileExists(depPath) { recompute dependency list or skip }

if err := sstDev(); err != nil {
	if strings.Contains(err.Error(), "failed to open file for hashing") {
		// file vanished or is unreadable: restart dev to rebuild dependency list
	}
}

When it happens

Trigger: copySyncedDependencies calls hashFileContents(path) on a path that no longer exists (file deleted between dependency discovery and hashing) or is unreadable (permissions, symlink to nonexistent target, path too long).

Common situations: File removed by a concurrent build/clean while `sst dev` is syncing; stale cache pointing at an old dependency path; workspace package relocated or renamed; restrictive umask/permissions on files generated by another user (e.g. root in Docker).

Related errors

• failed to hash file: %w
• error walking target directory during cleanup: %w
• failed to read source directory: %w
• failed to create destination file: %w
• failed to copy file contents: %w

AI-assisted analysis of anomalyco/sst@a0bd20f762 (2026-08-30). Data as JSON: /api/errors/fba887c1b91efd87. Report an issue: GitHub.