# Python Requests Throwing Sslerror

When Python's `requests` library throws an `SSLError`, it typically indicates that the SSL/TLS handshake failed when trying to establish a secure connection to a remote server. This can happen for several reasons, including certificate verification issues, outdated SSL libraries, or problems with the server's SSL configuration. Here are some common causes and how to resolve them:

### 1. **Certificate Verification Failure**

The most common reason for an `SSLError` in `requests` is a failure to verify the SSL certificate of the remote server.

### Solution: Disable SSL Verification (Temporary Fix)

You can bypass SSL certificate verification by setting the `verify` parameter to `False`. However, this should only be used for testing purposes as it exposes your connection to potential security risks.

```python
import requests

response = requests.get('<https://example.com>', verify=False)
print(response.content)
```

**Warning:** Disabling SSL verification is not recommended for production code due to security concerns.

### Solution: Provide a CA Bundle

If you want to maintain security and properly verify certificates, you can provide a custom CA bundle. You can use the `certifi` package to handle SSL verification:

```bash
pip install certifi
```

Then use it in your code:

```python
import requests
import certifi

response = requests.get('<https://example.com>', verify=certifi.where())
print(response.content)
```

### 2. **Outdated or Missing CA Certificates**

If the CA certificates on your system are outdated, `requests` may not be able to validate the server's certificate.

### Solution: Update CA Certificates

- **On Windows**: Ensure that your system's CA certificates are up-to-date. You can also use the `certifi` package as mentioned above.
- **On Linux/macOS**: Update your system's CA certificates using your package manager:
    - **Debian/Ubuntu**:
        
        ```bash
        sudo apt-get install --reinstall ca-certificates
        ```
        
    - **Fedora/CentOS/RHEL**:
        
        ```bash
        sudo yum reinstall ca-certificates
        ```
        
    - **macOS (Homebrew)**:
        
        ```bash
        brew install openssl
        ```
        

### 3. **Server-Side Issues**

Sometimes, the issue lies with the server's SSL/TLS configuration, such as using an unsupported or outdated protocol.

### Solution: Use a Different SSL Protocol

You can force `requests` to use a different SSL version by using the `urllib3` library, which `requests` is built upon.

```python
import requests
from urllib3 import PoolManager
from requests.adapters import HTTPAdapter
from requests.packages.urllib3.util.ssl_ import create_urllib3_context

class SSLAdapter(HTTPAdapter):
    def __init__(self, ssl_version=None, **kwargs):
        self.ssl_version = ssl_version
        super(SSLAdapter, self).__init__(**kwargs)

    def init_poolmanager(self, *args, **kwargs):
        context = create_urllib3_context(ssl_version=self.ssl_version)
        kwargs['ssl_context'] = context
        return super(SSLAdapter, self).init_poolmanager(*args, **kwargs)

session = requests.Session()
adapter = SSLAdapter()
session.mount('https://', adapter)

response = session.get('<https://example.com>')
print(response.content)
```

You can specify the `ssl_version` by passing it to `create_urllib3_context`.

### 4. **Expired or Revoked Certificates**

If the server's certificate has expired or been revoked, `requests` will throw an `SSLError`.

### Solution: Contact the Server Administrator

If the server's certificate is indeed expired or revoked, the best course of action is to contact the server administrator to have it renewed or replaced.

### 5. **System Time Incorrect**

SSL/TLS certificates have a validity period. If your system clock is incorrect, the certificate might appear invalid.

### Solution: Sync System Time

Ensure your system clock is set correctly:

- **Windows**: Adjust the date and time settings from the Control Panel.
- **Linux/macOS**: Use `ntpdate` or another time synchronization tool.

```bash
sudo ntpdate -u time.nist.gov
```

### 6. **Intermediary Issues (e.g., Proxy or Firewall)**

A proxy or firewall might be intercepting the SSL traffic and causing the error.

### Solution: Bypass or Configure the Proxy/Firewall

- Check if your system uses a proxy or firewall that intercepts SSL.
- Configure `requests` to use the correct proxy settings, or bypass the proxy if possible.

```python
proxies = {
    "http": "<http://proxy.example.com:8080>",
    "https": "<https://proxy.example.com:8080>",
}

response = requests.get('<https://example.com>', proxies=proxies)
print(response.content)
```

### Summary

`SSLError` in Python's `requests` library typically arises from SSL/TLS handshake failures due to certificate verification issues, outdated libraries, or server misconfigurations. You can temporarily bypass the error by disabling SSL verification, but the recommended approach is to use proper CA certificates or update your system's SSL configuration. Debugging the issue by checking certificate details, system time, and any intermediary network devices can also help in resolving the problem.