# Troubleshooting

Find the cause of connection failures, transaction errors, missing functions and slow queries.

Source: https://particledb.ai/guides/troubleshooting/

| Symptom | Check first | Next step |
|---|---|---|
| Connection refused | The server is running and the configured address is correct | [Connections](/operations/connections/) |
| Authentication fails | User, password, TLS and the selected authentication method | [Authentication](/connectivity/tls/) |
| Table not found | Database, schema, spelling and the active search path | [Schemas](/getting-started/databases-and-schemas/) |
| Transaction conflict | SQLSTATE and whether the entire transaction was retried | [Transactions](/sql/transactions/) |
| Queries fail after one error | The connection still has an aborted transaction | Run `ROLLBACK`, then retry the intended operation |
| Particle not found | Module deployment, function name and supported runtime | [Loading Particles](/particles/loading/) |
| Particle fails | Input types, dependencies, permissions and execution limits | [Particle limits](/particles/limits/) |
| Query is slow | Query plan, record count, indexes and resource pressure | [Performance](/guides/query-performance/) |
| Data is missing after restart | The same data directory and persistence configuration were used | [Durability](/operations/durability/) |

## Capture useful information

Record the server and client versions, the failing operation, its error code and a minimal reproduction. Remove credentials, customer data and private identifiers before sharing diagnostics.

## Check health

```bash
curl --fail http://localhost:7173/health
```

A healthy response shows that the endpoint responds. It does not prove that every query or external dependency is healthy.

## Related

[Documentation home](/docs/) · [Troubleshooting](/guides/troubleshooting/)