Updating AI plugin fails

Contribute Bug
,

AI-generated summary

Users reported an issue where updating Discourse with the AI plugin installed causes a database error: PG::UndefinedColumn: ERROR: column llm_models.url does not exist. This occurs when upgrading from a version lacking migration 20240514171609 to a newer commit (8d5f901 or later). The root cause is that plugin.rb calls LlmModel.enable_or_disable_srv_llm! during db:migrate, which fails if the url column doesn’t yet exist — crashing the migration before it can complete. RGJ noted that core catches PG::UndefinedTable but not PG::UndefinedColumn, explaining why the issue only arises on updates, not fresh installs. Three potential fixes were proposed: conditionally skip the call during migrations, rescue the error, or extend core to catch PG::UndefinedColumn. Roman acknowledged the report and pushed a fix in post 5. RGJ confirmed the fix works perfectly. The issue is now resolved.

1

Distilling this from Latest update won't build due to various reasons since that topic is about three different issues at the moment.

Problem:

When trying to update Discourse with the AI plugin installed, the update yields an error with

PG::UndefinedColumn: ERROR:  column llm_models.url does not exist
LINE 1: SELECT "llm_models".* FROM "llm_models" WHERE "llm_models"

and renders Discourse unusable until the AI plugin is removed.

When does this happen:

When updating an instance with the AI plugin
From a version that does not have the migration 20240514171609 yet
To commit 8d5f901 or newer

(My main question was why this only happens when updating an already-installed plugin and not when the plugin is newly installed. The answer is that core catches PG::UndefinedTable exceptions but not PG:UndefinedColumn. If the plugin is already installed then the exception is the latter, if the plugin is brand new then it is the former).

Reason:

plugin.rb calls LlmModel.enable_or_disable_srv_llm! which depends on the column llm_models.url being present. But if migration 20240514171609 (which adds that column) has not been applied yet, it crashes.

The problem is that db:migrate also runs this code, which crashes the rake task before the migration can be applied.

Suggested workarounds / fixes:

  1. change the code to LlmModel.enable_or_disable_srv_llm! if Discourse.running_in_rack? (so db:migrate does not call it)
    or
  2. change the code to LlmModel.enable_or_disable_srv_llm! rescue nil (so it does not crash)
    or
  3. change the bootstrapping code in core to catch PG::UndefinedColumn in addition to PG::UndefinedTable (so this and future similar issues are caught)

@Roman

6 Likes
Latest update won't build due to various reasons
4

Thanks for letting us know, @RGJ. I’ll take care of this and update once it’s fixed.

7 Likes
5

Pushed a fix here:

https://github.com/discourse/discourse-ai/pull/708

Let me know if you still have problems, please.

5 Likes
6

Works like a charm! Thank you :slight_smile:

3 Likes