“Engine unavailable” for Python scripts, or “This script is set to … but the code is written in …”

What you see

On the Scripting page, the engine strip shows “Engine unavailable” with “Measured: the engine did not start. Python scripts stay on hold; your JavaScript scripts are unaffected.” followed by the reason, and a “Try again” button. Separately, running a script may show “This script is set to Python, but the code in it is written in JavaScript. It will fail with a syntax error pointing at an arbitrary line.” (or the reverse) with “Switch to {detected}”.

Why it happens

The Python engine (Pyodide) is not shipped inside the app. “Install the Python engine” downloads its files once from senzoukria.com, the only remote origin the app’s security policy allows, stores them locally and starts the interpreter in the sandbox. It fails when the download cannot complete, when local storage refuses the files (“indexedDB unavailable”, “write refused”, “file missing from the cache”), or when the engine files do not have the expected shape. Once installed, it runs entirely offline.

The mismatch message comes before any run: switching language never translates code, so a JavaScript body labelled Python would fail on an arbitrary line.

How to fix it

• Check your internet connection and click “Try again”.
• If it fails again at the same point, restart the app and click “Try again”.
• For the mismatch, click “Switch to {detected}”, or rewrite the code in the declared language.
• Keep using JavaScript scripts meanwhile; they need no engine and run in the same sandbox.

What it is not

• Not a problem with your script’s logic: the engine did not start.
• Not a network use by scripts: scripts never have network access.

When to contact support

When none of this helps, write to support through Menu → Report a problem or on the Senzoukria Discord. Copy the reason shown after “Engine unavailable” and your operating system.