Hi, my service was deploying successfully using a Dockerfile for several weeks.

Starting today (Mar 12), deployments are suddenly failing with:

"Railpack could not determine how to build the app"

"Script start.sh not found"

Nothing changed in our code or Dockerfile between the last working deploy and the first failed one. Our railway.json explicitly sets builder: "DOCKERFILE"

but Railpack appears to be ignoring it and running auto-detection instead.

Service: courageous-sparkle / shopify_railway / production

Build logs from first failed deploy:

- Found .dockerignore file, applying filters

- Script start.sh not found

- Railpack could not determine how to build the app.

Attempted fixes (all failed with "Error creating build plan with Railpack"):

- Added railway.toml with builder = "dockerfile"

- Added railpack.json with {"builder": "dockerfile"}

- Added nixpacks.toml with apt packages and start command

The builder setting in the service Settings page appears locked/unclickable.

Did Railway migrate from Nixpacks to Railpack for this service automatically?

If so, what is the correct configuration format to use our Dockerfile with Railpack?

Our Dockerfile is in the project root and was working fine until today. Thanks :)