docker/cli · error

failed to cast to expected type: %w

Error message

failed to cast to expected type: %w

What it means

Error "failed to cast to expected type: %w" thrown in docker/cli.

Source

Thrown at cli/compose/interpolation/interpolation.go:71

	}

	return out, nil
}

func recursiveInterpolate(value any, path Path, opts Options) (any, error) {
	switch value := value.(type) {
	case string:
		newValue, err := opts.Substitute(value, template.Mapping(opts.LookupValue))
		if err != nil || newValue == value {
			return value, newPathError(path, err)
		}
		caster, ok := opts.getCasterForPath(path)
		if !ok {
			return newValue, nil
		}
		casted, err := caster(newValue)
		if err != nil {
			return casted, newPathError(path, fmt.Errorf("failed to cast to expected type: %w", err))
		}
		return casted, nil

	case map[string]any:
		out := map[string]any{}
		for key, elem := range value {
			interpolatedElem, err := recursiveInterpolate(elem, path.Next(key), opts)
			if err != nil {
				return nil, err
			}
			out[key] = interpolatedElem
		}
		return out, nil

	case []any:
		out := make([]any, len(value))
		for i, elem := range value {
			interpolatedElem, err := recursiveInterpolate(elem, path.Next(PathMatchList), opts)

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at cli/compose/interpolation/interpolation.go:71 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/ab458ced7bd87826.json. Report an issue: GitHub.