---
title: "Troubleshoot a failed connection | Grafana Labs"
description: "Diagnose a failed Save & test when connecting a data source"
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

## When Save & test fails, check these first

A failed connection test usually comes down to a handful of causes:

| Check                                       | Why it’s common                                                                                                        |
|---------------------------------------------|------------------------------------------------------------------------------------------------------------------------|
| URL, port, and protocol (`http` or `https`) | The wrong port or endpoint is a leading cause of connection failures.                                                  |
| Credentials and token scope                 | Auth errors often look like connection errors. Confirm the account or token has the permissions the data source needs. |
| Network reachability                        | Grafana must be able to reach the endpoint over the network. A firewall, VPC, or private network can block access.     |

> **Tip:** Read the exact error message. A `401` or `403` points to credentials or permissions, while a timeout or “connection refused” points to networking.

* * *

## Learn more

The data source troubleshooting guide covers connection, authentication, and query errors in detail.

[Troubleshoot data sources](https://grafana.com/docs/grafana/latest/datasources/troubleshooting/)