---
meta:
  title: "The type you provided for 'RoomEvent' is not a valid JSON value"
  parentTitle: "Error"
  description: "Your 'RoomEvent' type is incorrect and needs to be updated"
---

## Why this error occurred

You have provided a custom `RoomEvent` type for your application, but the type
you provided isn’t a (completely) valid JSON value. Values like `Date`, `Map`,
`Set`, functions, classes, or `unknown` aren’t valid JSON.

For example, suppose you have defined three broadcastable events for your
application:

```ts highlight="4-7"
declare global {
  interface Liveblocks {
    RoomEvent:
      | { type: "beep" }
      | { type: "boop"; target: HtmlElement }
      //                        ^^^^^^^^^^^ ❌ The issue is here
      | { type: "buzz"; volume: number };
  }
}
```

In the example above, the problem is in the `HTMLElement` field, because a
`HTMLElement` isn’t a valid JSON value.

## How to fix it

You’ll need to figure out what part of your provided `RoomEvent` type definition
isn’t valid JSON. Sometimes this is immediately obvious, but sometimes the issue
may be a bit less obvious.

## If you cannot find the root cause

Sometimes types can be complex and the root cause is still unclear. In those
cases, there is a small trick you can use. Try to assign your type to the
required base type, with this line:

```ts highlight="9-10"
import type { Json } from "@liveblocks/client";

declare global {
  interface Liveblocks {
    RoomEvent: MyRoomEvent;
  }
}

// Quick debugging snippet to find root cause
const xxx: Json = {} as MyRoomEvent;
//    ^?
//    The error will appear here
```

Now TypeScript will explain why it thinks your type isn’t valid JSON:

```error showLineNumbers={false}
Type 'MyRoomEvent' is not assignable to type 'Json'.
  Type '{ type: "boop"; target: HTMLElement; }' is not assignable to type 'Json'.
    Type '{ type: "boop"; target: HTMLElement; }' is not assignable to type 'JsonObject'.
      Property 'target' is incompatible with index signature.
        Type 'HTMLElement' is not assignable to type 'Json | undefined'.
          Type 'HTMLElement' is not assignable to type 'JsonObject'.
            Index signature for type 'string' is missing in type 'HTMLElement'.
```

---

For an overview of all available documentation, see [/llms.txt](/llms.txt).