# Preview deployment not created for a fork branch (/help-center/preview-deployment-not-created-for-fork-branch) 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](/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 [#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](/deploy/preview-deployments#fork-pull-requests) for details.