[Rozwiązany] [Prusa Connect] Invalid Endpoint URL error in Channels Setup for Telegram bot channel  

RE: [Prusa Connect] Invalid Endpoint URL error in Channels Setup for Telegram bot channel

Managed to resolve this. tldr; Telegram API instability is the root cause. Steps to resolve, for those who are interested:

1. Revoke the current token, and generate a new one.
2. Using the new token, send a "getMe" message to check that the bot is authorized to access Telegram API. Should receive something like the following as a response:

   {"ok":true,"result":{"id":<your id>,"is_bot":true,"first_name":"your_bots_name","username":"your_bots_username","can_join_groups":true,"can_read_all_group_messages":false,"supports_inline_queries":true}}%   

3. Use the `sendMessage` method to send a test message. For example:

   curl "https://api.telegram.org/bot<your_token>/sendMessage?chat_id=<your_chats_id>&text=Hello%20from%20curl"

4. You should receive a response. For some undetermined reason, Telegram replied with the following:

   {"ok":false,"error_code":400,"description":"Bad Request: group chat was upgraded to a supergroup chat","parameters":{"migrate_to_chat_id":-<another_chat_id>}}%

5. Now all that is left to do is to change the original chat-id to the one that was supplied in the previous step.
6. Enter those values in the form provided by Prusa Connect.