ALERTMANAGER-0.33.1 release notes and known issues

0.33.1 / 2026-07-04

Scope: Prometheus Alertmanager. This update record adds version, fix and known-issue context. Its publication date is not a lifecycle boundary.

Summary

[BUGFIX] doc: fix missing notification_reason field in webhook documentation ( #5329 ) [BUGFIX] silences: fix silences snapshot missing legacy matchers field. This caused a bug that prevented older alertmanager versions from reading newer snapshots unnecessarily. ( #5330 ) [BUGFIX] silence with no matchers should populate an empty array in API response ( #5331 )

Improvements and security content

[BUGFIX] doc: fix missing notification_reason field in webhook documentation ( #5329 ) [BUGFIX] silences: fix silences snapshot missing legacy matchers field. This caused a bug that prevented older alertmanager versions from reading newer snapshots unnecessarily. ( #5330 ) [BUGFIX] silence with no matchers should populate an empty array in API response ( #5331 )

Known issues

Publisher statement

Not stated. The verified publisher record does not contain a known-issues statement.

Affected products and versions

Products

Prometheus Alertmanager

Affected versions

0.33.1

Fixed versions or updates

No fixed version is stated in this record.

Recommended action

Review the official publisher document before deployment.

Official publisher evidence

PROMETHEUSVERIFIED

0.33.1 / 2026-07-04

Checked 29 Sep 2026. BlackTree preserves the last verified facts if a later source check is temporarily unavailable.

Open the official publisher source