"Nothing to install, update or remove" how to install this module ?

How to transition from using Drupal core Forum module to contrib version, and similar questions would be great to get documented.

So perhaps this issue could be turned into a documentation issue, and the result added to a fresh README file → ?

I would guess that the method should be something like this:

1. Update to the latest version of Drupal core
2. Delete the Drupal core Forum module
3. Download the contrib version with Composer
4. Rebuild caches, and possibly extra steps →
5. Run drush updatedb

Of course, only try this on a backup first, and not an actual live, production web site.

It would be great to get feedback from a maintainer, whether the steps above are correct.

PS. Composer uses different words, which can muddy things, but in Drupal:

• "Download" = Composer - download or delete a module
• "Install" = Drush, or under /extend

Is drupal/forum in your composer.json?

@larowlan: It seems to me not trivial to switch from core to contrib, see #3499865-15: Deprecate the Ban module → .

... or is simply running composer require drupal/forum enough for you?

I don't know sorry, I haven't used the module in a decade

Since my comment, I have realized that rebuilding caches more thoroughly than with the standard methods (like with drush cache:rebuild) may be required. Deleting the old core module, however is not a requirement.

I have added a new section "How to replace a deprecated core module with its contrib version": https://www.drupal.org/docs/core-modules-and-themes/deprecated-and-obsol... →

Though, thinking more about this, a user who does not clear caches via the settings.php trick may in fact still be using files from core/modules/forum, even if contrib/forum is downloaded. There's no real way to tell if one or the other is in use, as far as I can tell ...

Or, I guess visiting the Extend page and checking if Forum module is listed or not under "Core" modules section could work as a method?

Does that make it clearer what needs to be done @freelylw? Like @larowlan asked, can you see drupal/forum in the composer.json file? Is Forum module listed or not under Core modules on the Extend page? (Ideally it should only be included as a standard contrib module)

By the way @larowlan, to verify this, I use DDEV with a fresh Drupal 10 instance, install Forum, and then simply download drupal/forum, and do the rest of the steps. Just to clarify that this is not an existing installation, but a plain vanilla instance.