> ## Documentation Index
> Fetch the complete documentation index at: https://docs.unlink.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Error handling

> Handle the UnlinkError hierarchy, including timeouts and transient connection loss.

All SDK errors extend `UnlinkError` with a `code` discriminator. Four subclasses
ship: `ApiError`, `CapabilityError`, `ValidationError`, and `TimeoutError`.

```ts theme={null}
import { ApiError, TimeoutError } from "@unlink-xyz/sdk/browser";

// Same shape from /client or /admin.

try {
  const tx = await client.deposit({ token, amount });
  await tx.wait({ timeoutMs: 60_000 });
} catch (err) {
  if (err instanceof TimeoutError) {
    console.error("Confirmation timed out:", err.txId);
  } else if (err instanceof ApiError) {
    console.error("Engine rejected:", err.code, err.detail);
  } else {
    throw err;
  }
}
```

Use `CapabilityError` for missing local setup, such as a missing EVM provider or
an account that cannot execute. Use `ValidationError` for invalid SDK inputs.

The `ApiError` class also covers transport failures. If a connection drops
mid-response, the SDK throws `ApiError` with `code: "CONNECTION_LOST"` instead
of leaking a raw `TypeError`. It is distinct from an Engine rejection,
transient, and safe to retry. The underlying error is attached as `err.cause`.