How can I fix the 'The session “{id}” is not registered' error in n8n's Telegram Trigger?

Based on the details you provided, it looks like your issue may be related to the reverse proxy setup. In some cases with the Telegram Trigger node, test mode can appear to be stuck and issues like "The session “{id}” is not registered" may occur if the websocket connection isn’t working as expected.

Here are a few points to check and troubleshoot:

• Websocket support:
  When running n8n behind a reverse proxy (such as Nginx), you need to make sure that websocket proxying is correctly configured. Without this, the Trigger node may get stuck waiting for events and the session registration can fail.
  For example, if you’re using Nginx, verify that you have set the proper headers:

  NGINXCopied
  location / {
      proxy_pass http://YOUR_N8N_INSTANCE;
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";
      proxy_set_header Host $host;
      proxy_cache_bypass $http_upgrade;
  }

• Webhook URL configuration:
  Make sure that you have configured the WEBHOOK_URL environment variable to match your instance's public HTTPS URL. For Telegram, the webhook URL must be HTTPS. If this isn’t set properly, Telegram may not be able to register the webhook, which can cause unexpected errors.

• Resetting the workflow:
  When you see that test mode is stuck (or you can’t stop it), try exiting the workflow and reopening it to ensure that the canvas is reset.

By double-checking your reverse proxy’s websocket settings and confirming that you are using the correct public URL with HTTPS for the WEBHOOK_URL, you should be able to resolve the issue.