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

# Preview deployment not created for a fork branch

> Why fork pull requests and fork branches passed to the preview API do not produce preview deployments, and how maintainers can preview fork changes.

If a pull request opened from a fork shows no preview deployment link, this is expected behavior. The same is true if a call to the [Trigger preview deployment](/docs/api/preview/trigger) endpoint with a fork branch fails. Mintlify does not build preview deployments from fork branches.

The Mintlify GitHub App must be installed on a repository to build a preview. The app is installed on your main repository, not on contributor forks, so it cannot read a fork or build a preview against it. This applies to both automatic pull request previews and previews triggered through the API. The `branch` value in an API request must exist in the repository connected to your Mintlify project.

## Preview changes from a fork

A maintainer with write access to the main repository can push the fork's branch to the main repository, then open a pull request from that branch or pass that branch name to the API. See [Fork pull requests](/docs/deploy/preview-deployments#fork-pull-requests) for details.


## Related topics

- [Assistant](/docs/assistant/index.md)
- [GitLab](/docs/deploy/gitlab.md)
- [Deployments](/docs/deploy/deployments.md)