At this time, you can link to either GitHub, GitLab, or Bitbucket via the Netlify User Interface. However, there is an issue with Bitbucket that causes pull request (PR) deploy previews to fail. This is due to a shortcoming in the Bitbucket API, whereby our system doesn’t get provided all the information it needs to pull your code for a pull request via Bitbucket's API, and thus, we cannot fetch or build it, or show you previews. Bummer. If you are interested, Bitbucket has an article providing more insight into this issue.
GitHub and GitLab's APIs are capable in this regard, and allow us to show you a preview, but not Bitbucket's.
If you plan to continue using Bitbucket + Netlify, I'd suggest disabling the notifications for pull requests on the Netlify webhook in your repository's settings to prevent future failed builds.
Bitbucket works well with Netlify otherwise!
If this issue is resolved, we’ll post an update here. If you think your issue is a result of something else, give us a shout and we’ll try and help.