> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nuon.co/llms.txt
> Use this file to discover all available pages before exploring further.

# Roll back an install

> Re-apply a previous app config version to one install, or to a whole deployment group, with a plan in front of it.

Every config change to an install is recorded as an app config version, and any earlier version can be applied again.
That is the recovery path when a rollout, or a mistyped input, turns out badly.

You will need an API token (create one in the dashboard's org settings), your org ID, and the install's ID from
`nuon installs list`.

## Roll back one install

<Steps>
  <Step title="List the install's versions">
    ```sh theme={null}
    curl -H "Authorization: Bearer $NUON_API_TOKEN" \
      -H "X-Nuon-Org-ID: $NUON_ORG_ID" \
      "https://api.nuon.co/v1/installs/$INSTALL_ID/app-config-versions"
    ```

    Each entry carries the app config it pinned. The install's **Versions** view in the dashboard shows the same
    history.
  </Step>

  <Step title="Confirm what changed">
    ```sh theme={null}
    curl -H "Authorization: Bearer $NUON_API_TOKEN" \
      -H "X-Nuon-Org-ID: $NUON_ORG_ID" \
      "https://api.nuon.co/v1/installs/$INSTALL_ID/app-config-versions/$VERSION_ID/diff"
    ```
  </Step>

  <Step title="Apply the older version">
    ```sh theme={null}
    curl -X POST \
      -H "Authorization: Bearer $NUON_API_TOKEN" \
      -H "X-Nuon-Org-ID: $NUON_ORG_ID" \
      -H "Content-Type: application/json" \
      -d '{"app_config_id": "'"$OLD_APP_CONFIG_ID"'"}' \
      "https://api.nuon.co/v1/installs/$INSTALL_ID/app-config-updates"
    ```

    Send `{"plan_only": true}` alongside it first if you want to see the plan without applying.
  </Step>
</Steps>

## Roll back a deployment group

To move a whole deployment group back rather than one install, trigger a branch run against the older app config and
skip the build step, since the artifacts for that config already exist:

```sh theme={null}
curl -X POST \
  -H "Authorization: Bearer $NUON_API_TOKEN" \
  -H "X-Nuon-Org-ID: $NUON_ORG_ID" \
  -H "Content-Type: application/json" \
  -d '{"app_config_id": "'"$OLD_APP_CONFIG_ID"'", "skip_builds": true}' \
  "https://api.nuon.co/v1/apps/$APP_ID/branches/$APP_BRANCH_ID/runs"
```

The run still plans each group and still waits for approval, so you see the reverse diff before it is applied.

<Note>
  This is a pattern built from the version history and the branch run API, not a one-click button. Nothing about it is
  automatic: you choose the version and you approve the plan.
</Note>

## See also

* [App branches](/concepts/app-branches) — how runs, groups, and version history fit together.
* [Configure app branches](/guides/app-branches) — set up the branch this recovery path builds on.