Discourse-automation did not send PM: no valid targets exist

pangbo · February 11, 2026, 4:16am

I saw some warnings in the logs that discourse-automation plugin failed to send PMs. Automation plugin uses the usernames at the time of triggering the trigger, rather than the latest usernames of users when sending PMs. Since the PM-sending script supports delayed sending, users may change their usernames after the trigger and before the PM is sent, resulting in failures.

I think changing DiscourseAutomation::PendingPm to record user IDs instead of usernames can solve this issue:

github.com/discourse/discourse

plugins/automation/app/models/discourse_automation/pending_pm.rb

d10b6be86


      
          # == Schema Information
          #
          # Table name: discourse_automation_pending_pms
          #
          #  id               :bigint           not null, primary key
          #  execute_at       :datetime         not null
          #  raw              :string
          #  sender           :string
          #  target_usernames :string           is an Array
          #  title            :string
          #  created_at       :datetime         not null
          #  updated_at       :datetime         not null
          #  automation_id    :bigint           not null

Regarding my use case:

I have a task to send PMs to new users after a delay, configuring the automation plugin to send PMs five minutes after users join the TL0 group. However, some new users change their usernames immediately after registration, resulting in sending failures.

sam · February 11, 2026, 6:04am

It is a surprisingly tricky rabbit hole that goes pretty deep.

When you finish digging you discover that a fundamental construct we had PostCreator never supported user ids

github.com/discourse/discourse

FEATURE: support target_user_ids for private messages (#37708)

main ← automation-lookup

opened 06:03AM - 11 Feb 26 UTC

SamSaffron

+231 -35

Add `target_user_ids` as an alternative to `target_usernames` when creating priv…ate messages via PostCreator and TopicCreator. The two options are mutually exclusive and raise ArgumentError if both are provided. This avoids username-based lookups where the caller already has user IDs, and prevents stale references when users rename after a pending PM is created. Key changes: - PostCreator/TopicCreator: accept `target_user_ids`, validate mutual exclusivity with `target_usernames`, extract shared `add_users_from_scope` in TopicCreator - Automation PendingPm: migrate from `sender`/`target_usernames` string columns to `sender_id`/`target_user_ids` integer columns with a backfill migration - Scriptable::Utils.send_pm: resolve sender upfront, support integer sender param, store IDs in pending PMs

I think it is a great change cause everything is a lot less surprising. Users tend to do a bit of username renaming when they start off.

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Discourse-automation did not send PM: no valid targets exist

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