A chat channel says it failed

From Teams up

Open the channel's delivery log: Settings, Notifications, then Delivery log beside the channel. The error beside each message says what went wrong. If the service answered with a code in the 400s other than 429, the webhook is gone or the URL is wrong. Make a new webhook in the service and add the channel again. After most other errors, we try again by ourselves.

Where a failure shows

Only admins see shared channels, and only admins see these messages.

The Alerts page shows a banner for each channel whose last message failed, with the reason.
The Notifications page shows the same reason under the channel, in the Shared channels section.
The channel's Delivery log lists the latest messages, newest first. Each row has the time it was queued, the alert it was about, its result and the error.

The banner and the error stay until a message to the channel goes through. A test sent with Send test that goes through clears them too.

What each result means

Waiting: queued. A chat channel waits 10 minutes first, so that alerts which come together arrive in one message. A message that failed and will be tried again also shows Waiting, with the reason for the last failure beside it.
Sent: the service accepted the message. If you cannot find it, look in the channel or chat that the webhook posts to.
Failed: we stopped trying. The error says why.
Not sent: we did not post it. By the time it was due, the channel was turned off, the plan no longer included the channel or that kind of alert, the alert was turned off for the domain, or the domain was removed. Today, a row skipped because of the plan also shows the error "We could not post to the service." Nothing was posted, and the only fix is a plan that includes the channel or the alert.

A channel marked Paused by the plan receives nothing until the organization is on a plan with shared channels again. Its messages show Not sent.

Errors we do not retry

These fail at once. Trying again would not help.

"The service answered 404. Check the URL, or make a new webhook in the service." The number can be any code from 400 to 499 except 429. A deleted webhook answers 404. Add the channel again with a new URL.
"We could not read this channel's settings. Delete it and add it again." Add the channel again.
"We could not build the message for this alert, so it was not sent." The fault is ours. Write to support with the time and the channel's name.

A test sent with Send test is tried once, whatever the error.

Errors we retry

We try a message 5 times in all. The waits between tries are, in order: 1 minute, 5 minutes, 30 minutes, 120 minutes. A message that still fails after the last try shows Failed.

These usually pass by themselves. If they last for hours, look at the service's own status page.

"The service is receiving too many messages and asked us to wait." The service answered 429.
"The service answered 503, which is an error on its side." The number can be any code from 500 up.
"The service did not answer within 5 seconds."
"We could not connect to the service.", "The TLS connection to the service failed." or "The service sent an answer we could not read."
"We could not post to the service." Any other failure.

These three are retried too, but they do not go away until the URL changes:

"The host name in the URL does not resolve." The host in the URL no longer exists in DNS.
"The URL points at a private or reserved address. We only post to public addresses." The host leads to an address on a private network. A Mattermost server, for example, has to be reachable from the internet.
"The URL redirects. Use the address it redirects to." Use the address it leads to.

For each, add the channel again with a URL that works.

Add the channel again with a new URL

A channel's URL cannot be changed. Add a new channel, then delete the old one.

In the service, make a new incoming webhook for the same chat, and copy its URL. For Telegram, you need the bot token and the chat ID instead.
Open Settings, Notifications. Under Shared channels, fill in the form and press Add channel. Leave Send every alert here ticked to add the channel to every alert of the domains you have now. Otherwise, choose it on each domain's Alerts page.
Press Send test on the new channel. The Not tested mark goes away after the first test that goes through.
Press Delete channel on the old channel. Its delivery log is deleted with it.

If the old channel also got a summary, choose it again for the new channel with Send a summary here.

The usual causes

Slack: the webhook was removed, or the app it belongs to was removed from the workspace.
Microsoft Teams: the workflow that holds the webhook was deleted.
Discord and Google Chat: the webhook was deleted from the channel or the space.
Telegram: the bot was removed from the chat, or its token was changed.

Summaries in a channel

A summary posted to a channel is not in its delivery log, and a failed one does not show the banner. If a summary fails, we do not post it again for that period. The next summary covers the next period.

Published 27 October 2026 · Checked 27 October 2026