Hey! This is happening because mise can't find a precompiled binary for Python 3.12.13 on your architecture x86_64-unknown-linux-gnu). It's likely that 3.12.13 is either very new or not yet available as a prebuilt binary in mise's registry.

Here are a couple of things you can try:

1. Pin a slightly older patch version — try using python@3.12.12 (or whichever was the latest working one) in your .mise.toml or .tool-versions file. Patch versions are backward-compatible so this shouldn't break anything.

2. Use a looser version constraint — instead of pinning the exact patch like 3.12.13, just use 3.12 so it grabs whatever latest 3.12.x precompiled binary is available.

3. Force mise to compile from source — if you really need that exact version, set the environment variable MISE_PYTHON_COMPILE=1 in your Railway service variables. This tells mise to build Python from source instead of looking for a prebuilt binary. Keep in mind this will make builds slower. More info here: https://mise.jdx.dev/lang/python.html#precompiled-python-binaries

Also worth noting — Railway now uses Railpack as the default builder (Nixpacks is deprecated). If you haven't migrated yet, that might be worth looking into as well: https://docs.railway.com/builds/railpack

For configuring packages and environment variables on Railway builds, check out: https://docs.railway.com/builds/build-configuration