hashicorp/terraform · critical

unknown value type in TypeMap %T

Error message

unknown value type in TypeMap %T

What it means

Panics in SerializeValueForHash (serialize.go:64) when hashing a TypeMap value. The inner switch over each map value supports only int, float64, and string; any other concrete Go type (bool, []interface{}, map, struct) panics.

Source

Thrown at internal/legacy/helper/schema/serialize.go:64

		sort.Strings(keys)
		buf.WriteRune('[')
		for _, k := range keys {
			innerVal := m[k]
			if innerVal == nil {
				continue
			}
			buf.WriteString(k)
			buf.WriteRune(':')

			switch innerVal := innerVal.(type) {
			case int:
				buf.WriteString(strconv.Itoa(innerVal))
			case float64:
				buf.WriteString(strconv.FormatFloat(innerVal, 'g', -1, 64))
			case string:
				buf.WriteString(innerVal)
			default:
				panic(fmt.Sprintf("unknown value type in TypeMap %T", innerVal))
			}

			buf.WriteRune(';')
		}
		buf.WriteRune(']')
	case TypeSet:
		buf.WriteRune('{')
		s := val.(*Set)
		for _, innerVal := range s.List() {
			serializeCollectionMemberForHash(buf, innerVal, schema.Elem)
		}
		buf.WriteRune('}')
	default:
		panic("unknown schema type to serialize")
	}
	buf.WriteRune(';')
}

View on GitHub (pinned to c9def3e214)

Solutions

1. Ensure map values are limited to string/int/float.
2. Coerce booleans to strings ("true"/"false") before they reach the hashing path.
3. Avoid nesting lists/objects as direct map values; model them as nested blocks instead.

Example fix

// before
set.Add(map[string]interface{}{"enabled": true})
// after
set.Add(map[string]interface{}{"enabled": "true"})

func mapValuesHashable(m map[string]interface{}) error {
    for k, v := range m {
        switch v.(type) {
        case int, float64, string: continue
        default: return fmt.Errorf("map key %s has non-hashable value type %T", k, v)
        }
    }
    return nil
}

When it happens

Trigger: A TypeMap containing a non-{int,float64,string} value (e.g. a bool or a nested structure) that gets hashed because the map is an element of a parent TypeSet.

Common situations: Provider tests or custom code building sets-of-maps with bool/struct values; legacy map values that were not string-coerced before hashing.

Related errors

• unknown schema type to serialize
• invalid element type: %T
• missing field in set: %s.%s
• set item just set doesn't exist
• invalid set element type

AI-assisted analysis of hashicorp/terraform@c9def3e214 (2026-08-07). Data as JSON: /api/errors/cdddfc72792e5a3f. Report an issue: GitHub.