Cannot assign to read only property 'Symbol(Symbol.metadata)'

[iar5]

AgoraRTC SDK version

4.19.0

Fail Rate

100%

Link to minimal reproduction

https://stackblitz.com/edit/vitejs-vite-p9wrtoyz?file=package.json,tsconfig.json,src%2Fmain.ts&terminal=dev

Steps to reproduce

Description

• Using @colyseus/schema@^3.0.0 together with any module from agora-rtc-sdk-ng@4.19.0 triggers the following error.
• Even calling a single method—e.g. AgoraRTC.setLogLevel(4);—is enough to reproduce it.
• Colyseus Schema’s @type decorator writes metadata to Function.prototype[Symbol.metadata].
• However, Agora’s SDK appears to freeze or override Symbol.metadata, preventing Colyseus from attaching decorator metadata.
• As a result, when both libraries are imported, Colyseus’s attempt to write to Symbol.metadata fails with a TypeError.

---

Reproduction

1. Open the minimal StackBlitz project:
   https://stackblitz.com/edit/vitejs-vite-p9wrtoyz?file=package.json,tsconfig.json,src%2Fmain.ts&terminal=dev
2. Click “Open Preview in New Tab” (top-right corner of the preview pane).
3. Open DevTools in that new tab. You will immediately see the error in the console.

---

Error

index.js:950 Uncaught TypeError: Cannot assign to read only property 'Symbol(Symbol.metadata)' of function 'class MyTestState extends Schema {
  constructor() {
    super(...arguments);
    this.testString = "test";
    …<omitted>…
  }
}'
    at Object.initialize (index.js:950:40)
    at index.js:2954:39
    at __decorateClass (index.ts:7:24)
    at index.ts:8:18

---

Key Questions

• Why does Agora’s SDK freeze or override Symbol.metadata?
• Can that behavior be changed so it does not conflict with other decorator-based libraries like Colyseus Schema?

What is expected?

No crash

What is actually happening?

Crash

System Info

Any additional comments?

No response

[iar5]

Fixing this bug will enable developers to seamlessly integrate Agora’s voice and video into their Colyseus based games, driving wider adoption of Agora in the multiplayer gaming space.