## Connection issues

URL: https://docs.atlan.com/apps/connectors/database/cratedb/troubleshooting/connection-issues

> Resolve common connection and authentication issues when setting up CrateDB connector

This guide helps you resolve common connection and authentication issues when setting up the CrateDB connector in Atlan.

## Unable to connect to CrateDB cluster

If Atlan can't establish a connection to your CrateDB cluster, you see connection errors during the initial setup or test connection phase.

**❌ Error messages**
```
Check failed - Unable to connect to CrateDB cluster
Connection timed out
```

**🔍 Cause**
- Incorrect HTTP/HTTPS endpoint format
- Firewall blocking port `4200` (or your configured port) 
- SSL/TLS certificate errors when using HTTPS

**🛠️ How to fix**

1. **Verify endpoint format**: Make sure you're using the correct HTTP or HTTPS endpoint with proper format:
 ```
 http://your-host:4200
 https://your-cluster.crate.io:4200
 ```

2. **Check firewall and port access**: Port `4200` must be open between Atlan and your CrateDB instance.

3. **Validate SSL certificate**: If using HTTPS, make sure the certificate is valid and trusted by your network.

---

## Authentication failed

When credentials are incorrect or the user account has issues, authentication fails preventing Atlan from accessing your CrateDB cluster.

**❌ Error messages**
```
Check failed - Authentication failed for user <username>
401 Unauthorized
```

**🔍 Cause**
- Wrong username or password
- User not present in CrateDB
- Password expired or changed

**🛠️ How to fix**

1. **Verify credentials**: Double-check that the username and password are correct.

2. **Veriy user exists**: Confirm user exists in CrateDB with:
 ```sql
 SELECT name FROM sys.users WHERE name = 'atlan_user';
 ```

3. **Update password**: Reset user password with:
 ```sql
 ALTER USER atlan_user SET (password = 'new_password');
 ```

---