# SDKError.fatal

```ts
readonly fatal: boolean
```

`true` means the SDK itself is unusable: the engine failed to load (`ENGINE_LOAD_FAILED`) or the SDK stopped on an unrecoverable fault (`ENGINE_FAILED`), or `init()` was never called. Re-initialize, or stop. Everything else is `false` — the one operation failed and the SDK and the viewer are as they were: a page that did not render, a file that would not open (`CORS_ERROR`, `NETWORK_ERROR`, `FORMAT_ERROR`, `PASSWORD_ERROR`, `SECURITY_ERROR` — offer another file), an argument a call could not act on. `fatal` never says "the document is unusable"; the code does.

- Kind: property
- Since: 1.0.0

Returns `boolean`

```ts
viewer.on('error', ({ code, message, fatal }) => {
  if (fatal) showReloadPrompt();
});
```

Part of [SDKError](https://kernstra.com/docs/web-sdk/api/sdkerror) in the Kernstra Web SDK 1.0.0 API reference.

Web page: https://kernstra.com/docs/web-sdk/api/sdkerror/fatal