I use a "tags" taxonomy for most content on my site. The "Forum" (core) module insists on using its own vocabulary ("Forums") and also seems to have automatically created a vocabulary for itself.

Is there a way to have the forum module use my existing "tags" vocabulary? I'd imagine forum topics tags with a tagged term to be listed in a teaser kind of preview when browsing that tags' vocabulary's matching term (alongside other content with that tag).

Edit: See below screenshot where I try to change the vocabulary in the forum content type field. The vocabulary choice is disabled. enter image description here

1 Answer 1


After you enable the D7 core Forum module, you'll also have a "Forum topic" content type (and a "Forums" vocabulary as shown via admin/structure/taxonomy/forums).

Using the "Manage fields" tab of this content type (located at /admin/structure/types/manage/forum/fields), you can see the various fields for this content type. One of its fields is the "Forums" field (with machine name "taxonomy_forums"), with "Term Reference" as Field type.

Click the "Term Reference" link of the "Forums" field there, which brings you to /admin/structure/types/manage/forum/fields/taxonomy_forums/field-settings, where you can change its "Field settings".

There you will be able to change the (default) "Forums" vocabulary to (e.g) your existing "Tags" vocabulary (or any other vocabulary you have defined).

Attention: if on the "Field settings" screen the Vocabulary drop down is disabled (= you cannot select another vocabulary, as in the screenprint in the "PS" of the question), and you get an error message like "There is data for this field in the database. The field settings can no longer be changed.", then you'll have to think of a way to get around it somehow. A few more links that provide some more details on this (and possibly other alternatives):

Be careful when trying to get this fixed! Because things may get worse ... You might consider a possible approach like this:

  1. Create a new term reference Field for the Forum topic content type, and for which you then select the desired taxonomy.
  2. After that, it should be OK to "delete" the original taxonomy_forums (machine name) field.

However, in doing so, the new term reference Field will have a machine name starting with a prefix field_. But if you then try to use that field (as part of the Forum module functionality), the Forum module might not use such field_ prefix (you might get errors about that mismatch).

An alternative approach might be to uninstall/reinstall the Forum module, and then check if after enable you can change the taxonomy term field. However, in doing so, be aware that the taxonomy term "General discussion" of the taxonomy "Forums" (used by the module) is NOT deleted as part of the uninstall of the module. So before re-install (enable), you may want to try to manually delete that term and taxonomy first. If you don't do that, then you might end up with a taxonomy term like "General discussion" multiple times.

  • Thanks for the instructions. I've made it that far, but for some reason my Vocabulary drop down is disabled in the last screen (see my updated question with image). Why would that be?
    – kontur
    Oct 11, 2015 at 17:23
  • I've enhanced my answer with the "Attention" part of it. Curious to hear if you can get around that roadblock somehow ... Oct 11, 2015 at 17:50
  • I'm currently in developing stage, so neither the forum taxonomy nor other contents need to be kept... would wiping all existing topic and taxonomies help to make the drop down selectable again?
    – kontur
    Oct 29, 2015 at 13:52
  • I'm hot sure, and I haven't tried it myself so far, but if I were you I would indeed try such approach. Eventually in a cloned version of your current DEV site, which could be as easy as temporary making it a multi-site, which uses the same code base (core, contrib, custom modules). And with an exact copy of the database of your current DEV site (in a separated database). As an alternative try to uninstall/reinstall the forum module as I suggest in my last parg of my answer (also in such cloned DEV site if need)? Oct 29, 2015 at 13:59
  • Thanks so much for your detailed suggestions. Deleting all forum topic contents in the admin panel allowed me to change the vocabulary for the forum as you described. Perfect answer.
    – kontur
    Nov 1, 2015 at 11:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.