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

## Why this error occurred

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

<Banner type="success" title="What was LSON again?">

LSON is either a valid JSON value, or an instance of `LiveMap`, `LiveList`,
`LiveObject`, or `LiveFile`.

</Banner>

```ts highlight="6"
declare global {
  interface Liveblocks {
    Storage: {
      layers: LiveMap<string, LiveObject<Layer>>;
      layerIds: LiveList<string>;
      createdAt: Date; // ❌ The issue is here
    };
  }
}
```

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

## How to fix it

You’ll need to figure out what part of your provided `Storage` type definition
isn’t valid LSON. Sometimes this is immediately obvious, like in the example
above.

Sometimes the issue may be a bit less obvious:

```ts highlight="7-8"
import type { Lson } from "@liveblocks/client";

declare global {
  interface Liveblocks {
    Storage: {
      layers: LiveMap<string, LiveObject<Layer>>;
      layerIds: LiveList<unknown>; // ❌ Unknowns could contain non-LSON
      layerIds: LiveList<Lson>; // ✅ Prefer using Lson
    };
  }
}
```

By using `Lson`, you can still work with unknown or unspecified values, but
still ensure they will be valid LSON.

## 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 { LsonObject } from "@liveblocks/client";

declare global {
  interface Liveblocks {
    Storage: MyStorage;
  }
}

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

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

```error showLineNumbers={false}
Type 'MyStorage' is not assignable to type 'LsonObject'.
  Property 'layerIds' is incompatible with index signature.
    Type 'LiveList<unknown>' is not assignable to type 'Lson | undefined'.
      Type 'LiveList<unknown>' is not assignable to type 'LiveList<Lson>'.
        The types returned by 'toArray()' are incompatible between these types.
          Type 'unknown[]' is not assignable to type 'Lson[]'.
            Type 'unknown' is not assignable to type 'Lson'.
```

---

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