Client started, but nothing happens¶

If your client starts without errors but handlers never fire, the most common causes are:

No event loop running — Make sure you are using app.run() or asyncio.run() rather than calling app.start() without a running loop.
Handler not registered — Double-check that your @app.on_message() decorators are placed before app.run().
Filters are too restrictive — Try removing all filters temporarily to confirm the handler fires at all.
Bot privacy mode — If you are using a bot in a group, ensure privacy mode is disabled via BotFather, or add the bot as an admin.