# Chatbot

These blocks work with the person's contact in the chatbot: the bot writes to the person, starts a scenario for them, tags the contact.

**When there is a contact.** There is a contact when the app is opened from the bot — in Telegram, MAX or a website chat — and the person has written to that bot. A guest from a browser has no contact. In that case the block goes through the "No contact" exit: lead it to a screen with a hint to open the bot.

**Which bot.** The bot is connected to the app in "Settings" — see [Versions and publishing](https://support.watbot.org/mini-apps/publish#connect-a-bot). Without connected bots, the "Bot scenario" block shows the hint "No bot is linked to the app — link one in the app settings.".

The "No contact" exit also fires on other block failures — an empty message, a scenario not found, no tags set. The reason gets into the [error log](https://support.watbot.org/mini-apps/users#error-log).