When running server: "TypeError: Cannot read property 'types' of undefined"

Hi, I'm running into a persistent error when trying to run a colyseus server. It starts up fine, but when I try to connect to the server from the client, I get the following error:

> ts-node src/index.ts

[gltd-server] running environment:  local
~you are now globally limited~
[gltd-server] Listening on 2657
TypeError: Cannot read property 'types' of undefined
    at Function.Reflection.encode (/Users/brianableson/gltd/globally.ltd/server/node_modules/@colyseus/schema/src/Reflection.ts:96:47)
    at SchemaSerializer.handshake (/Users/brianableson/gltd/globally.ltd/server/node_modules/colyseus/lib/serializer/SchemaSerializer.js:57:70)
    at Club.<anonymous> (/Users/brianableson/gltd/globally.ltd/server/node_modules/colyseus/lib/Room.js:292:136)
    at Generator.next (<anonymous>)
    at fulfilled (/Users/brianableson/gltd/globally.ltd/server/node_modules/colyseus/lib/Room.js:5:58)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)

I am closely following this example.

Here is my current package.json file:

  "name": "globally-ltd-game-server",
  "version": "0.0.1",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start-local": "NODE_ENV=local onchange 'src/**.ts' -i -d 1000 -- ts-node src/index.ts",
    "start-ts": "ts-node src/index.ts",
    "start": "ts-node src/index.ts",
    "test": "echo \"Error: no test specified\" && exit 1"
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@types/cors": "0.0.33",
    "@types/express": "^4.17.6",
    "@types/node": "^13.11.1",
    "onchange": "^3.3.0",
    "ts-node": "^7.0.1",
    "typescript": "^3.8.3"
  "dependencies": {
    "colyseus": "^0.12.6",
    "cors": "^2.8.1",
    "express": "^4.14.0",
    "onchange": "^3.3.0"

I'm new to typescript, so i'm guessing this is a noobish problem but i'm having trouble googling for the error. Thanks so much for your help in advance!

I am seeing this relevant post but am having trouble figuring out exactly what was changed:


@globallyltd I have this error when I use and empty State. Then I try create a property in that state object and it works.

@boygiandi Could you paste some code please, I'm having the same trouble but I can't fix it with your method :/

Hi @Estournet

Apparently you need to have some field inside your state:

import { Schema, type } from "@colyseus/schema";

class YourState extends Schema {
  @type("string") xxxx;

I'll check what can I do on the next version to prevent this error from happening. Let me know if that fixes for you.


Hi @endel

Okay I figured out how to do. I had this trouble and I am using plain JS, which adds more trouble :p (and I hadn't read the documentation about State, I have to admit)
So, if anyone has the same trouble, here is a solution for plain Javascript :

import { Room } from "colyseus";
// Imports need to be done with require for Schema
const schema = require('@colyseus/schema');
const { defineTypes, Schema } = schema;

export class TestState extends Schema {
  foo = "bar";
  anything = "you want"

export class TestRoom extends Room {
  onCreate(options) {
    this.setState(new TestState());

// This is the important part
defineTypes(TestState, {
  whatever: "string"

Thanks for the help !