As far as I know is that a limitation in Telegram & n8n. You can only register a single Webhook at any given point at Telegram. So if we would allow to run a test execution while the workflow is active (which we did in the past), would it result in the production webhook being unregistered, and production executions would stop working.
We sadly do not have a mechanism in n8n right now that would overwrite URL and after test set again production one.
So for now, what you would need to do is:
- Disable workflow
- Run Test Execution
- Enable workflow
I hope we can improve that at some point!
Thanks for the reply from your busy life 
I have tried that but still not able to do it.
So what I tried to do was create a webhook trigger (POST) to fetch messages from telegram, but aha not able to get message
Ig i’m too dumb
Not sure I understand. You are not using the Telegram Trigger Node?
No worries, i just figured it out thanks jan