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

# Error Handling Pattern

> Recommended pattern for handling all transaction failure modes in CosmJS.

A robust transaction flow should handle all three failure modes — CheckTx
rejection, timeout, and execution failure:

```typescript theme={"system"}
import {
  SigningStargateClient,
  GasPrice,
  TimeoutError,
  BroadcastTxError,
  isDeliverTxSuccess,
  Coin,
} from "@cosmjs/stargate";

async function sendTokens(
  client: SigningStargateClient,
  sender: string,
  recipient: string,
  amount: readonly Coin[],
): Promise<string> {
  try {
    const result = await client.sendTokens(sender, recipient, amount, "auto");

    if (isDeliverTxSuccess(result)) {
      return result.transactionHash;
    }

    // Execution failed (out of gas, insufficient funds, etc.)
    throw new Error(
      `Transaction ${result.transactionHash} failed with code ${result.code}: ${result.rawLog}`,
    );
  } catch (error) {
    if (error instanceof BroadcastTxError) {
      // CheckTx rejection — do not retry without fixing the issue
      throw error;
    }

    if (error instanceof TimeoutError) {
      // Transaction may still succeed — query later
      console.warn("Transaction submitted but not yet confirmed:", error.txId);
      throw error;
    }

    throw error;
  }
}
```

## Error Summary

| Stage                 | Error type          | Retryable?               | Key fields                   |
| --------------------- | ------------------- | ------------------------ | ---------------------------- |
| Encoding              | `Error`             | No                       | Fix input data               |
| Signing               | `Error`             | No                       | Fix wallet/key setup         |
| Transport (HTTP)      | `Error`             | Often                    | `cause.status`, `cause.body` |
| Transport (WebSocket) | `Error`             | Reconnects automatically | —                            |
| CheckTx               | `BroadcastTxError`  | Rarely                   | `code`, `codespace`, `log`   |
| Block inclusion       | `TimeoutError`      | Query later              | `txId`                       |
| DeliverTx             | `DeliverTxResponse` | Depends                  | `code`, `rawLog`, `events`   |
| Query                 | `Error`             | Depends                  | Error message                |
| Simulation            | `Error`             | Fix input                | Error message                |

## Next Steps

<CardGroup cols={2}>
  <Card title="Error Classes" icon="arrow-right" href="/cosmjs/v0.38.x/concepts/errors/error-classes">
    Explore CosmJS error types and their properties.
  </Card>

  <Card title="Transaction Errors" icon="arrow-right" href="/cosmjs/v0.38.x/concepts/errors/transaction-execution">
    Handle CheckTx failures and execution errors.
  </Card>
</CardGroup>