We are changing how Python Workers are structured by default. Previously, handlers were defined at the top-level of a module as on_fetch, on_scheduled, etc. methods, but now they live in an entrypoint class.

Here's an example of how to now define a Worker with a fetch handler:

from workers import Response, WorkerEntrypoint

class Default(WorkerEntrypoint):
    async def fetch(self, request):
        return Response("Hello World!")

To keep using the old-style handlers, you can specify the disable_python_no_global_handlers compatibility flag in your wrangler file:

• wrangler.jsonc

  {
    "compatibility_flags": [
      "disable_python_no_global_handlers"
    ]
  }

• wrangler.toml

  compatibility_flags = [ "disable_python_no_global_handlers" ]

Consult the Python Workers documentation for more details.