hashicorp/terraform · critical

Unknown type: %s

Error message

Unknown type: %s

What it means

A panic in `MapFieldReader.ReadField` (internal/legacy/helper/schema/field_reader_map.go:38), default branch of the switch over `schema.Type`. The flat-map-backed reader dispatches TypeBool/TypeInt/TypeFloat/TypeString/TypeList/TypeMap/TypeSet/typeObject; any other Type panics with 'Unknown type: %s'. This reader is used when a schema is read from a flat key/value map source (e.g. raw state attributes), so the panic reflects a malformed provider schema Type encountered during map-source reads.

Source

Thrown at internal/legacy/helper/schema/field_reader_map.go:38

	schemaList := addrToSchema(address, r.Schema)
	if len(schemaList) == 0 {
		return FieldReadResult{}, nil
	}

	schema := schemaList[len(schemaList)-1]
	switch schema.Type {
	case TypeBool, TypeInt, TypeFloat, TypeString:
		return r.readPrimitive(address, schema)
	case TypeList:
		return readListField(r, address, schema)
	case TypeMap:
		return r.readMap(k, schema)
	case TypeSet:
		return r.readSet(address, schema)
	case typeObject:
		return readObjectField(r, address, schema.Elem.(map[string]*Schema))
	default:
		panic(fmt.Sprintf("Unknown type: %s", schema.Type))
	}
}

func (r *MapFieldReader) readMap(k string, schema *Schema) (FieldReadResult, error) {
	result := make(map[string]interface{})
	resultSet := false

	// If the name of the map field is directly in the map with an
	// empty string, it means that the map is being deleted, so mark
	// that is is set.
	if v, ok := r.Map.Access(k); ok && v == "" {
		resultSet = true
	}

	prefix := k + "."
	r.Map.Range(func(k, v string) bool {
		if strings.HasPrefix(k, prefix) {
			resultSet = true

View on GitHub (pinned to c9def3e214)

Solutions

1. Audit the provider schema and set a valid Type on every attribute.
2. Add provider schema-construction tests asserting no TypeInvalid entries.
3. Keep SDK and provider versions in sync.
4. If migrating schemas, ensure old flat-map state fields map to attributes with valid Types.

Example fix

null

// Go (provider): validate schema Types the map reader will encounter
for name, s := range resource.Schema {
    switch s.Type {
    case schema.TypeString, schema.TypeBool, schema.TypeInt, schema.TypeFloat,
         schema.TypeList, schema.TypeMap, schema.TypeSet:
    default:
        return fmt.Errorf("map reader cannot handle schema %q Type %d", name, s.Type)
    }
}

// Go: confirm a Type is map-reader-compatible
func mapReadableType(t schema.ValueType) bool {
    switch t {
    case schema.TypeString, schema.TypeBool, schema.TypeInt, schema.TypeFloat,
         schema.TypeList, schema.TypeMap, schema.TypeSet:
        return true
    }
    return false
}

When it happens

Trigger: Reading a field from a flat map source (KV state attributes) when the schema attribute's Type is outside the recognized ValueType set — unset (TypeInvalid) or an unknown constant.

Common situations: Provider schema with an unset/invalid Type; SDK version drift; reading legacy flat-map state for a field whose schema Type is not a known scalar/collection/object constant.

Related errors

• Unknown type: %s
• Unknown type: %s
• Unknown type: %#v
• invalid Schema.Type %s
• unknown type: %#v

AI-assisted analysis of hashicorp/terraform@c9def3e214 (2026-08-07). Data as JSON: /api/errors/3f7fe502f665b35c. Report an issue: GitHub.