Telegram Webhook Checker

A Telegram bot gets new messages in one of two ways: Telegram pushes each update to a URL you registered (a webhook), or your code asks for them with getUpdates. getWebhookInfo is the one call that tells you which mode the bot is in and how delivery is going. Three fields carry nearly all the signal.

url is the registered endpoint. Empty means polling mode. pending_update_count is how many updates Telegram is holding for the bot right now. last_error_message and last_error_date record the most recent failed delivery, in Telegram's own words - "Wrong response from the webhook: 502 Bad Gateway", "Connection timed out", an SSL verification error. This checker turns each of those into a cause and a fix, and draws the pipeline so you can see which hop is broken.

Telegram delivers updates in order and keeps retrying the oldest one until your endpoint returns a 2xx status. One bad update, a crashed handler or a server that answers too slowly therefore stalls everything behind it, and the count climbs. Common causes, roughly in the order we see them:

• The endpoint returns an error status. A 500 from an unhandled exception, a 502 when the app behind the proxy is down, a 404 after a route was renamed. Every one counts as not delivered.
• The handler is slow. Work done before replying - calling an AI model, a database, another API - can outlast Telegram's patience. Reply 200 at once and process in the background.
• The certificate does not verify. A missing intermediate certificate passes in many browsers but fails for Telegram.
• Polling with no poller. No webhook is set and nothing calls getUpdates, so updates simply wait.

Once the endpoint is healthy the queue drains by itself - turn on Watch above to see it fall in real time. Anything still undelivered after 24 hours is discarded by Telegram.

drop_pending_updates, available on both setWebhook and deleteWebhook, throws the whole queue away. It is the right move when the backlog is stale - a bot that was down for a day should not answer yesterday's "hello" - or when one malformed update keeps crashing your handler and you need delivery moving again now. It is the wrong move when those updates are orders, payments or support requests you still owe a reply. Fix the endpoint first, watch the queue, and drop only what you can afford to lose.

Switching between modes is the other common job. If getUpdates answers 409 Conflict, a webhook is still registered: delete it above and polling works. Rate limits that can also make a bot look silent are on the Telegram limits page, and a wider checklist lives in why your Telegram bot is not responding.

The durable pattern is short: an HTTPS endpoint on port 443 with a certificate from a public authority, a secret_token checked on every request, a 200 returned before any slow work, and an alert when pending_update_count climbs. If you would rather not own that endpoint at all, a hosted Telegram chatbot registers and watches the webhook for you, and the token checker confirms a token is alive before you start.