I wanted to add a keyword for automatic tagging, so I went to /admin/customize/watched_words/action/tag to add a new keyword and tag, but an error popped up.
I checked the browser requests, and it looks like there is a problem with frontend serialization.
I’m using the latest version of Discourse (Discourse v2026.3.0-latest — Commits · discourse/discourse · GitHub). I enabled safe mode, and the issue still persists.