# sql: connection has been closed

- **ID:** `go/database-sql-conn-max-lifetime`
- **Domain:** go
- **Category:** data_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

A database connection is used after it has been closed due to exceeding ConnMaxLifetime, causing errors on subsequent queries.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.22 | active | — | — |

## Workarounds

1. **** (85% success)
   ```
   db.SetConnMaxLifetime(30 * time.Minute); db.SetMaxOpenConns(100); db.SetMaxIdleConns(10)
   ```

## Dead Ends

- **** — Can cause stale connections and resource leaks. (70% fail)
- **** — database/sql manages connections; manual reuse is not supported. (90% fail)