# sqlalchemy.exc.ArgumentError: Could not parse rfc1738 URL from string 'postgresql://user:pass@localhost/db'

- **ID:** `python/sqlalchemy-exc-argument-error-unknown-dialect`
- **Domain:** python
- **Category:** config_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

The database URL provided to create_engine() is malformed or missing required components like driver or host.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **Correct URL format with driver** (95% success)
   ```
   Use the correct format: 'postgresql+psycopg2://user:pass@localhost:5432/dbname'
   ```
2. **Use connect_args dictionary** (85% success)
   ```
   Use a dictionary for connection parameters instead of URL, e.g., create_engine('postgresql+psycopg2://', connect_args={'host': 'localhost'})
   ```

## Dead Ends

- **Adding extra slashes** —  (60% fail)
- **Using wrong driver name** —  (70% fail)