docker/cli · error

expected slice, got %T

Error message

expected slice, got %T

What it means

Error "expected slice, got %T" thrown in docker/cli.

Source

Thrown at templates/templates.go:137

		for i := range rv.Len() {
			if i > 0 {
				b.WriteString(sep)
			}
			_, _ = fmt.Fprint(&b, rv.Index(i).Interface())
		}
		return b.String(), nil

	case reflect.Map:
		var out []string
		for _, k := range rv.MapKeys() {
			out = append(out, fmt.Sprint(rv.MapIndex(k).Interface()))
		}
		// Not ideal, but trying to keep a consistent order
		sort.Strings(out)
		return strings.Join(out, sep), nil

	default:
		return "", fmt.Errorf("expected slice, got %T", elems)
	}
}

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at templates/templates.go:137 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/839d0a80c911a69b.json. Report an issue: GitHub.