This page gathers common issues that can happen before an application image is ready to start.

1. building Source fetched
2. building Technology detected
3. building Application image built
4. starting Container started
5. starting Postdeploy hook run
6. running  Application running

Unknown Technology

When pushing your app to Scalingo, you might get the following error:

<-- Start deployment of [my-app] -->
 !     We didn't find the type of technology you are using...
       We're sorry this build is failing!

       Refer to the documentation to find out why:
       https://doc.scalingo.com/deployment/unknown-technology

       If you can't find the issue in your application,
       please send us an email at support@scalingo.com

       <3,
       Scalingo
 !   Error deploying the application
 !   -> Invalid return code from buildpack

There are two main solutions to this problem.

Project in a Subdirectory (Monorepo)

Your project might be located in a subdirectory of your Git repository, which is common in monorepo setups. This is supported, but note that Scalingo’s deployment system looks at the repository root by default.

You need to setup the PROJECT_DIR environment variable for your application. See our dedicated page on environment variables.

You can find more information about monorepo deployment in our dedicated guide.

Technology Detection

To detect the technology used by your application, we iterate over the technologies alphabetically. It means that if your project contains multiple technologies, we will pick the first one detected.

If you want to skip the detection phase and force the use of a specific buildpack, add the environment variable BUILDPACK_NAME to your project.

If you need to use multiple technologies, you can use the multi-buildpacks.

You can also develop your own buildpack and add the environment variable BUILDPACK_URL to have complete control on the detection and build phases.

More information is available on buildpacks or multi-buildpacks.

Each language has its own expected files and conventions. Check the start page for your application language:

• Clojure
• Go
• Groovy
• Java
• Meteor
• Node.js
• PHP
• Python
• Ruby
• Scala

Git Submodule

If your project repository uses Git submodules, please be aware that Scalingo will not pull them. This Git feature is not supported on the platform for different reasons. The main reason being that we currently have no way to authenticate the git pull operation to a private Git repository when doing the deployment. Actually Git submodules are often considered as a broken feature of Git, that is why we do not encourage its usage or support it today.

We recommend you to vendor a specific release of the code of the sub-git repository in your main repository before pushing.

Build Errors

During the deployment process, Scalingo first builds your application: its dependencies are gathered and packaged into an application image.

Invalid Return Code From Buildpack

Your application image is built using a buildpack (List of buildpacks). If the buildpack exits with an error, it is probably linked to your project. You should be able to see the content of the error in your console. Then adapt your code according to it.

If you think the error comes from our buildpacks, feel free to contact us and we will fix it as soon as we can.

Image Too Large

The maximum size of an application image is 2 GiB. If your assets, your dependencies, and your application code exceed this limit, you need to reduce the size of the image before deployment:

• Try to remove unused external dependencies or assets.
• Define a .slugignore file to exclude files from the image.

If you absolutely need all this data, please contact our support team.

Archive Too Large

When deploying an application, the Scalingo build system downloads the source code as an archive. The maximum archive size is limited to 300 MB.

If your archive exceeds this limit you will get the following error:

Fail to fetch source code: fail to handle tgz: The archive is too heavy (more than 314572800 bytes)

If you need to deploy a larger archive, please contact our support team.