This plugin is now bundled with Discourse core and no longer needs to be installed. Next time you run a ./launcher rebuild app or update from Admin UI it will fail with the error:
bootstrap failed with exit code 128
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HINT: The plugin 'discourse-reactions' is now bundled with Discourse and should not be included in your container configuration.
Remove the line 'git clone https://github.com/discourse/discourse-reactions' from your containers/app.yml file, then try again.
For more information, see https://meta.discourse.org/t/373574
Ideally remove this plugin from your app.yml now to prevent problems when updating.
The same thing happened to me today when I updated. Not just reactions but quite a few plugins have now been bundled with core Discourse and so need to be removed from app.yml.
I’m not sure what the problem is here given that the error is very clear. I was surprised too but followed the directions in the error to remove the offending items and then rebuilt, and all was well.
I also thought the category chosen for the announcement was rather unusual. I don’t think anyone watches it because support questions are often asked there.
Maybe subcategories in announcements would be better, then you could inform hosting customers and self-hosters (and devs) separately. Everyone is informed about a release, but you can choose whether you want to be informed about all subcategories.
Also, a reply to the topic to bump it after the edit would have been helpful. Otherwise, it’s very easy to miss edits.
It’s not a huge problem, but it sucks to find out there’s a problem when doing a routine rebuild, eg for the next version upgrade.
For breaking changes in Discourse Core that affect theme components, we get advisories visible to Admins only for weeks in advance, allowing us to go and fix or remove those theme components. The same would be great for when it’s planned that a plugin will become Core.
For example, I know from this and and linked Topics that Data Explorer is going to be added into Core. That’s great. But I need a decent advisory/announcement on when that happens because I will remove it only when it’s included. Otherwise if I remove it now it risks there being a period of time withoutData Explorer.
최근 이 토론은 리액션 플러그인 토픽에서 #contribute:site-feedback으로 이동했습니다. 이는 코어로 이동하는 플러그인에 대해 이 사이트를 어떻게 활용하여 소통할지에 관한 내용이기 때문입니다. 이런 일은 가끔 발생하지만, 현재 인기 있는 많은 플러그인을 코어로 이동시키는 대규모 작업을 진행 중이며, 이는 많은 셀프호스터에게 영향을 미칠 것입니다. 이는 Bundling more popular plugins with Discourse core 에서 공지되었습니다.
@moin은 해당 공지 토픽을 #announcements에 게시하거나, 셀프호스터를 위한 공지사항을 위한 하위 카테고리를在那里 생성할 수 있다고 제안했습니다. 이 역시 좋은 아이디어입니다. 하지만 그러면 아무 조치도 취하지 않아도 되는 셀프서브 및 엔터프라이즈 호스팅 고객을 혼동시키지 않도록 주의해야 합니다.
영향을 받는 모든 플러그인의 토픽을 검토하여 설치 지침을 제거하고, 코어에 포함되어 있어 별도로 설치할 필요가 없음을 명시하며, included-in-core 태그를 부여해야 합니다.
@JammyDodgerincluded-in-core 태그의 의도가 무엇인지 상기시켜 주시겠어요? 특정 플러그인이 코어에 포함되어 있으며 app.yml에 추가하는 일반적인 방식으로 설치할 필요가 없다는 사실을 전달하기 위한 것인가요?
Yeah, it’s just a way to group those ones together and indicate that they’re the ‘bundled’ plugins. And it also serves as a marker for anyone who has the tag as Watching First Post so they get a heads up about any new ones.
So adding the tag, updating the install blurb, and leaving a fresh post to the plugin topic to say ‘good news everyone this is now bundled and doesn’t need to be installed separately, yada yada, remove from app.yml’ is usually the meta portion of things. (Maybe a slightly different flavour if something has genuinely moved into core rather than just bundled as a plugin). Getting that done as close to when it happens is the aim. Hopefully an admin dashboard message is also done as well, but that’s another thing.
For a fuller picture, there are still some inconsistencies with how bundled plugins are presented here on meta and in the UI. Some don’t have plugin topics (polls, Discobot, hide details, local dates, etc), and some are hidden from the plugin page on sites as well (chat, polls, Discobot, and so on). Smoothing those out would be nice so it’s more easily understandable for anyone new to know what’s what.
OK! I did the thing. Added the included-in-core tag, updated the OP, and added a reply. In some cases I found some updates that were needed to the OP too. Thanks @moin for your eagle eye to find problems.
Feel free to flag affected topics that need further fixing or updates. Otherwise I think we are caught up.
this is now bundled and doesn’t need to be installed separately, yada yada, remove from app.yml’ is usually the meta portion of things. (Maybe a slightly different flavour if something has genuinely moved into core rather than just bundled as a plugin). Getting that done as close to when it happens is the aim. 
Hopefully an admin dashboard message is also done as well, but that’s another thing.
eagle eye to find problems.