# Error Pages Bialet ships with built-in pages for the situations where no route is found and for when your code fails. You can replace both with your own HTML files — no Wren required. ## Default Pages When a request fails, Bialet returns a plain HTML page: | Situation | Status | Default page | |--------------------------------------------|--------|-----------------------| | No route matches the URL | 404 | Not found page | | A `.wren` file fails to parse or throws | 500 | Internal server error | The welcome page shown at `/` when the root has no `index.wren` or `index.html` is a separate page and cannot be customized this way. ## Custom Error Pages Drop an HTML file named after the status code in your app root directory. The server looks for it every time that error is produced: ```text my-site/ ├── index.wren ├── 404.html # served on every 404 └── 500.html # served on every 500 ``` Any file named `.html` in the root is used when Bialet renders that error. In practice that means `404.html` and `500.html`: ```html Page not found

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``` When a file is missing or an error occurs, Bialet reads the matching file and serves it with the correct HTTP status code and `Content-Type: text/html`. > ⚠️ Pitfall: the `.html` file is only read for errors Bialet > generates itself. If a `.wren` file calls `Response.status(404)` and > returns its own body, that body wins and `404.html` is not used. ## Scope Custom error pages are **static HTML only**. The file is served verbatim: - No `{{ ... }}` interpolation - No `_app.wren` template wrapping - No Wren execution > ⚠️ Pitfall: don't name the file `500.wren` expecting it to run. Bialet > does not execute `.wren` error pages; it only reads `.html` files. If your > error page must be dynamic, serve the error through your own `.wren` route > with `Response.status(...)` instead.