When deploying an application, if there is an issue detecting your application’s buildpack during the build process, you may see the following error in Deployment details.

Build process failed
Unknown build fail type

Click the error in Deployment details to see the build process log and look for errors similar to:

ERROR: No buildpack groups passed detection.
ERROR: Please check that you are running against the correct path.
ERROR: failed to detect: no buildpacks participating
ERROR: failed to build: executing lifecycle: failed with status code: 20

These errors occur when there isn’t enough information to correctly detect the type of application. This is usually caused by one of the following:

  • The Git repository doesn’t contain all the files needed for the application.
  • Something within the code or settings causes an incorrect buildpack to be selected.
  • The build path is incorrect.

Git Repository

Check your repository to ensure all the correct files have been pushed into the repository for your application.


If you choose Set up container image automatically when you add your application, we use a buildpack to automatically determine and set up a container for your application. If your application requires an additional buildpack, you can add additional buildpacks on your application’s Settings page.

When using buildpacks, you must also ensure the correct language version is in your application’s files. For more details, see our documentation on specifying a language version.

Build Path

The build path is where the files to build your application are located in the repository. Usually, this is the repository root, and you do not have to set a build path when adding your application.

If your application has a different build path, you can set that when you add the application, or you can change it in Settings (Settings > Edit details > Build path). For example, if your application needs to be built from a subdirectory named app, enter that subdirectory path as /app in the Build path field.

Related Documentation