# aiohttp.client_exceptions.ClientConnectorCertificateError: <url>

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

## Root Cause

SSL certificate verification failed for the target server, often due to self-signed certificates or expired CA chains.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.8 | active | — | — |
| 3.9 | active | — | — |
| 3.10 | active | — | — |
| 3.11 | active | — | — |
| 3.12 | active | — | — |

## Workarounds

1. **Use a custom SSL context with verification** (90% success)
   ```
   import ssl; ssl_ctx = ssl.create_default_context(); ssl_ctx.load_verify_locations('ca.pem')
connector = aiohttp.TCPConnector(ssl=ssl_ctx)
async with aiohttp.ClientSession(connector=connector) as session: ...
   ```
2. **Temporarily disable SSL verification for testing (not for production)** (70% success)
   ```
   connector = aiohttp.TCPConnector(ssl=False)
async with aiohttp.ClientSession(connector=connector) as session: ...
   ```

## Dead Ends

- **Disabling SSL verification entirely with connector=False** — This reduces security and may cause warnings; not recommended for production. (40% fail)
- **Ignoring the error and retrying without changes** — The same error will recur because the certificate issue is not addressed. (90% fail)