> ## 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.

# Transport Errors

> HTTP, WebSocket, and JSON-RPC errors between CosmJS and RPC nodes.

Transport errors occur between CosmJS and the RPC node. They depend on which
transport you use (HTTP or WebSocket).

## HTTP Errors

**Bad status (HTTP >= 400)**

Thrown by the low-level HTTP layer when the node responds with a non-2xx status.
The `cause` property carries the status code and response body:

```typescript theme={"system"}
try {
  const client = await StargateClient.connect("https://rpc.my-chain.network");
} catch (error) {
  // "Bad status on response: 429"
  const { status, body } = (error as Error).cause as { status: number; body: string };
}
```

Common status codes:

| Status          | Meaning                        | Action                                     |
| --------------- | ------------------------------ | ------------------------------------------ |
| 401 / 403       | Authentication required        | Add auth headers via `HttpEndpoint`        |
| 404             | Wrong URL or path              | Verify the RPC endpoint URL                |
| 429             | Rate limited                   | Back off and retry; use multiple endpoints |
| 502 / 503 / 504 | Server error / gateway timeout | Retry with exponential backoff             |

**Request timeout (AbortError)**

When an HTTP client is configured with a timeout, requests that exceed it throw a
`DOMException` with `name === "AbortError"`:

```typescript theme={"system"}
import { HttpClient } from "@cosmjs/tendermint-rpc";

const httpClient = new HttpClient("https://rpc.my-chain.network", 10_000); // 10s timeout
```

**Invalid URL**

Thrown immediately if the endpoint URL is missing a protocol:

```
"Endpoint URL is missing a protocol. Expected 'https://' or 'http://'."
```

## WebSocket Errors

**Connection timeout**

Thrown when the WebSocket handshake does not complete within the timeout
(default: 10 seconds):

```
"Connection attempt timed out after 10000 ms"
```

**Socket closed**

Thrown when sending on a closed or not-yet-open socket:

```
"Socket was closed, so no data can be sent anymore."
"Websocket is not open"
```

**Invalid URL**

```
"Base URL is missing a protocol. Expected 'ws://' or 'wss://'."
```

## JSON-RPC Errors

When the node returns a JSON-RPC error response, CosmJS throws an `Error` whose
message is the serialized error object. Standard JSON-RPC error codes:

| Code   | Meaning               |
| ------ | --------------------- |
| -32700 | Parse error           |
| -32600 | Invalid request       |
| -32601 | Method not found      |
| -32602 | Invalid params        |
| -32603 | Internal error        |
| -32000 | Server error (custom) |

## Reconnection

`WebsocketClient` uses `ReconnectingSocket` internally with exponential backoff
(100ms to 5s). HTTP clients do **not** retry automatically — implement retries
in your application if needed.