# aiohttp.client_exceptions.ClientConnectorSSLError: [SSL: WRONG_VERSION_NUMBER] wrong version number

- **ID:** `python/aiohttp-client-connector-ssl-handshake-error`
- **Domain:** python
- **Category:** network_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The server is using an incompatible SSL/TLS version, or the client is trying to connect with HTTPS to an HTTP server.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.10 | active | — | — |
| 3.11 | active | — | — |

## Workarounds

1. **Use the correct URL scheme (http:// instead of https://)** (90% success)
   ```
   async with session.get('http://example.com') as resp:
   ```
2. **Update the SSL context to use modern TLS versions** (85% success)
   ```
   import ssl
ssl_context = ssl.create_default_context()
ssl_context.minimum_version = ssl.TLSVersion.TLSv1_2
connector = aiohttp.TCPConnector(ssl=ssl_context)
async with aiohttp.ClientSession(connector=connector) as session:
   ```

## Dead Ends

- **Disabling SSL verification with ssl=False** — This does not fix the version mismatch; it only bypasses certificate verification. (50% fail)
- **Using a very old SSL context that forces TLS 1.0** — Many servers now reject outdated TLS versions due to security policies. (60% fail)