Set Topic Timer May Result in Catastrophic Failure

zogstrip · March 25, 2026, 3:09pm

Sorry about that @hellekin there were indeed a few bugs hidden in that feature

github.com/discourse/discourse

FIX: Prevent topic timer crashes when publishing to category (#38872)

main ← fix/topic-timer-publish-to-category

merged 02:49PM - 08 Apr 26 UTC

ZogStriP

+78 -10

Setting a "Schedule Publishing" topic timer without selecting a destination cate…gory could silently save the timer with the uncategorized category as the target and subsequently crash the topic page. The root cause was `set_or_create_timer` defaulting `category_id` to `SiteSetting.uncategorized_category_id` when not provided. The controller only passed `category_id` when present in params, so omitting it resulted in a valid (but wrong) timer being persisted. On the client side, if the saved category wasn't in the browser's category cache, `Category.findById()` returned undefined and the subsequent `.get("slug")` call threw a TypeError during rendering, which could destabilize the page. This commit: - Changes the default `category_id` in `set_or_create_timer` from `SiteSetting.uncategorized_category_id` to `nil`, so the existing model validation (`validates :category_id, presence: true, if: :publishing_to_category?`) rejects the record - Requires `category_id` in the controller when setting (not removing) a `publish_to_category` timer - Adds client-side validation in the modal before sending the request - Fixes a typo (`this.topicTime` → `this.topicTimer`) that caused stale timer state after removing a timer from the modal - Adds a null guard on `Category.findById()` in `TopicTimerInfo` so a missing category degrades gracefully instead of crashing https://meta.discourse.org/t/398284

Topic		Replies	Views
Topic timer causing error? Support tag-banners	1	232	April 1, 2024
Scheduled publishing renders topic unusable Bug	4	534	April 18, 2022
Draft topic with scheduled publication misses destination category UX shared-drafts	3	126	August 4, 2025
Scheduling topics for future publication Site Management topic-timers , how-to	0	18974	April 10, 2017
Issue with Publish to Category topic timer Support topic-timers	6	630	February 20, 2021

Set Topic Timer May Result in Catastrophic Failure

Related topics