Code 203

The `code203` error usually indicates that the client WebSocket connection could not be established successfully. In most cases, this is caused by network connectivity issues or incorrect WebSocket endpoint access.

## Symptom

The client fails during the connection process and reports `code203`.

## Cause

The required WebSocket connection cannot be established correctly. This usually happens because:
- The WebSocket address is incorrect.
- The target port is blocked by a firewall or security group.
- The network path between the client and the server is unavailable.
- A proxy, gateway, or external network policy is interfering with the connection.

## Solution

### Test the WebSocket Connection

Use an online WebSocket test tool to verify whether the target WebSocket address is reachable:

[WebSocket Online Test Tool](http://www.websocket-test.com/)

### Verification Steps

1. Open the online test tool.
2. If the page is already connected to a previous session, click **Disconnect** first.
3. Enter the target WebSocket connection address.
4. Click **Connect**.

![WebSocket connection example](https://docs.paraverse.cc/media/202504/5321073c1c7640eeb20202852315c0e91315.png)

5. If the connection succeeds, the message panel should display a message similar to:

```text
   Websocket connection has been established, waiting for data... 200
   ```

6. Send a test message.
7. If the message is received successfully, the WebSocket connection is working normally.

## Additional Checks

If the connection test fails, check the following:
- Whether the WebSocket URL is correct.
- Whether the required port is open.
- Whether the server is reachable from the client network.
- Whether firewall, proxy, or security-group rules are blocking the connection.