Latest.rss no longer works when using Babble

Product Support

AI-generated summary

The user romdos reports that the /latest.rss feed is broken, showing a blank page with an error: ActionView::Template::Error (undefined method name’ for nil:NilClass)inlist.rss.erb. After troubleshooting, [romdos](/t/-/77244/3) identifies that the issue is caused by a topic created by the Babble chat plugin that lacks a category. [vinothkannans](/t/-/77244/8) explains that the error occurs because topic.categoryisnil, which leads to the namemethod being called on anilobject. The error originates from line 20 oflist.rss.erb, where the category's name is accessed without checking if the category exists. [romdos](/t/-/77244/9) confirms that deleting the problematic topic resolves the issue. The discussion highlights how a missing category in a topic can cause unexpected errors in RSS feeds, and [vinothkannans](/t/-/77244/14) clarifies that the error message, while ambiguous, points to a nil` category object.

1

The RSS feed URL for Latest posts (/latest.rss) no longer works, and now just shows a blank page. Looking at the error logs I found this:

ActionView::Template::Error (undefined method `name' for nil:NilClass)
/var/www/discourse/app/views/list/list.rss.erb:20:in `block in _app_views_list_list_rss_erb___410690641174059981_69912794204760'

Here is the full text of the error log for this:
https://pastebin.com/jDDqZ5ND

2

Are You on the latest version?

Seems Specific to Your forum. Can’t repro this either on meta or on my own sandbox!

3

I’ve been running the newest available version, currently at v2.0.0.beta1 +4. The issue has been ongoing for about a month or so. I do have a few plugins I use, but doubt they’re the cause:

hooks:

  after_code:
    - exec:
        cd: $home/plugins
        cmd:
          - git clone https://github.com/discourse/docker_manager.git
          - git clone https://github.com/discourse/discourse-bbcode-color.git
          - git clone https://github.com/discourse/discourse-spoiler-alert.git
          - git clone https://github.com/gdpelican/retort
          - git clone https://github.com/cpradio/discourse-plugin-checklist.git
          - git clone https://github.com/discourse/discourse-solved.git
          - git clone https://github.com/iunctis/discourse-formatting-toolbar.git
          - git clone https://github.com/discourse/discourse-staff-notes.git
4

Shouldn't it be - git clone https://github.com/gdpelican/retort.git instead?

5

Good catch! I’ll change that now and rebuild..

Update: that wasn’t it.. Trying now with all plugins disabled.

6

Same issue with all plugins disabled (except docker_manager). :confused:

7

Perhaps this is beyond my understanding now. I hope someone more experienced may be able to help You with a better solution.

8

Looks like this topic is the cause of the issue.

9

Indeed. I deleted that topic and things are working again! To anyone else having this issue, the topic in question was created by the Babble chat plugin, which creates a topic without a category.

@vinothkannans how did you determine that was the source of the issue?

10

As per your error log one of your topic having null category value.

11

@vinothkannans I must be blind, because I don’t see how that was discerned from the error log. What line number exactly in the error log is indicating this? Thanks!

12

As per the first and second lines undefined method 'name' for nil:NilClass.

13

I guess what I’m asking is: how would anyone know/guess/decipher what is wrong based on that (IMHO, totally ambiguous) error message, without deep knowledge of Discourse?

undefined method 'name' (Okay there’s a undefined method called ‘name’ that is being called)
for nil:NilClass (this means nothing at all to me, should it?).

How does one interpret this error as having anything to do with a topic, let alone a topic without a category?

14

As I mentioned you should look at second line too. Error is coming from this line. So the topic.category should be nil.