Summary
In our Discourse instance, new posts and replies in topics are not appearing automatically. Users must manually refresh the page to see later posts, despite being actively viewing the topic.
This appears to be a regression in real-time updates (MessageBus/WebSocket/polling), as no themes, plugins, or custom components are installed.
Environment
• Discourse version: 2026.4.0-latest (9776b417b8)
• Hosting: self-hosted
• Custom theme: default
Steps to Reproduce
1. Open a topic in one browser/session
2. Open the same topic in another session/user account
3. Post a new reply in the topic
4. Observe the original session
Expected Behavior
New posts should appear in real-time without requiring a manual page refresh (via MessageBus updates / live topic updates).
Actual Behavior
New posts do not appear in the open topic view.
They only appear after:
• Manual browser refresh (F5 / reload), or
• Navigating away and back to the topic
Notes / Observations
• No custom plugins or themes that could interfere
• Appears consistent across users/sessions
• Issue affects visibility of later posts in a topic thread specifically
• Suggests possible regression or failure in:
• `MessageBus` subscription handling
• `/message-bus/ long polling / websocket` fallback
• topic update stream (`topic:reload`, `post:created`) propagation
Impact
• Breaks real-time discussion flow
• Causes users to miss new replies unless they refresh
• Creates confusion about whether posting succeeded or not
Request
Could you please confirm whether there is a known regression affecting real-time topic updates in recent builds, or advise on what subsystem to inspect (MessageBus, polling fallback, etc.)?