Tag 'Can't be used in this category' - when restricted tag

zogstrip · July 22, 2026, 2:26pm

Thanks for the report @AstonJ This’ll fix the issue and hopefully others by making it consistent across the app who can see / use which tags.

github.com/discourse/discourse

FIX: Allow selecting tags that are only used in personal messages (#41918)

main ← fix-pm-only-tags-selectable

merged 10:27AM - 24 Jul 26 UTC

ZogStriP

+363 -72

Previously, a tag whose only usage was in personal messages was silently dropped… by `TagsController.tag_counts_json` — a display rule from 2020 meant to keep such tags off the `/tags` browse page for users who cannot tag messages (and `pm_tags_allowed_for_groups` has no staff bypass, so by default that includes admins). Every surface reusing that method as a plain serializer inherited the rule by accident: - the composer tag search treated the missing row as unauthorized and showed the tag disabled with a bogus **"Can't be used in this category"** reason (the reported bug), - every "show all tags" chooser (tag groups, synonyms, watched tags, category allowed tags, webhooks, automations, …) silently refused to offer such tags at all, - the `#` autocomplete would not suggest a tag that nonetheless cooked into a working hashtag link when typed in full. This change makes `tag_counts_json` a pure serializer and moves the rule into an explicit, named helper (`DiscourseTagging.without_pm_only_tags`) applied only where it belongs — the `/tags` browse lists — with an exemption for the admin "show all tags" view so the admin inventory is complete. Selection and search surfaces now offer every tag the user is allowed to use, and tag-group visibility rules still apply everywhere. It also fixes two adjacent inconsistencies uncovered along the way: - **Topic→message conversion counter drift.** Converting only adjusted `public_topic_count`, so a converted topic's tags kept working until the periodic consistency job recounted them into the broken state — the "worked at first, broke a day later" in the report. The converter now moves all three counters immediately, and rolls back cleanly when the underlying post revision fails (its return value was previously ignored, and `Topic#valid?` clears the errors it adds, so a failed conversion still applied its side effects). - **Crawler/print tag leak.** The crawler layout leaked a message's tag names in the page title and `og:article:tag` metadata to participants the serializer already hides tags from; both now flow through `TopicView#visible_tags`, gated on `guardian.can_see_tags?`. Reported in https://meta.discourse.org/t/407050

Topic		Replies	Views
Restrict certain Tags to a category, but still allow that category to use all other Tags Feature	21	2160	January 9, 2026
CategoryTag no_content message doesn't describe what is happening UX	1	836	January 3, 2019
Limiting tags to categories not working as expected Bug tags	8	842	May 17, 2023
Restrict tags to specific categories Feature completed	16	5294	June 1, 2016
Limit category selections for topics based on tag restrictions Feature tags	2	319	October 12, 2023

Tag 'Can't be used in this category' - when restricted tag

Related topics