Why doesn't the Telegram Mini App open even though Telegram works?

Q: Why doesn't the Telegram Mini App open even though Telegram works?

Mini App access runs through a Cloudflare tunnel. If Cloudflare is unavailable on your network (at your provider, on mobile internet, with or without a VPN), the page will not open. The status is shown on the “Bot and chats” page: open the Mini App with the button in the bot when it says “Done”. If Cloudflare is blocked for you, it is better to untick “Enable Mini App”.

Bot and chats

Click a row — or a control on the picture — to read what it does.