Severe Email Issue since last update a couple days ago - 3.4.0.beta4-dev

I am having some new issues with email sending which have started in the last 4 days. Not sure whether best to continue this thread or start a new one, but for now will continue this one.

I had recently done a full site update from the command line around the time this issue occurred.

  • No users are being sent any notification emails about activity on the site.
  • SMTP sending seems to work fine, an email deliverability test worked instantly.
  • Sidekiq shows thousands of enqueued jobs which are retried regularly but are failing consistently. (7000+ jobs enqueued)
  • Logs show one very prominent and numerous error Job exception: UserDestroyer::PostsExistError - I have looked this up on Meta but nobody else having similar issues since at least 2017 when the last topic mentioned it. (9000+ errors all in the last 4 days)
Full stacktrace from logs
/var/www/discourse/app/services/user_destroyer.rb:18:in `destroy'
/var/www/discourse/app/jobs/onceoff/fix_primary_emails_for_staged_users.rb:23:in `block (2 levels) in execute_onceoff'
activerecord-7.2.2.1/lib/active_record/relation/delegation.rb:98:in `each'
activerecord-7.2.2.1/lib/active_record/relation/delegation.rb:98:in `each'
/var/www/discourse/app/jobs/onceoff/fix_primary_emails_for_staged_users.rb:21:in `block in execute_onceoff'
/var/www/discourse/app/jobs/onceoff/fix_primary_emails_for_staged_users.rb:14:in `each_key'
/var/www/discourse/app/jobs/onceoff/fix_primary_emails_for_staged_users.rb:14:in `execute_onceoff'
/var/www/discourse/app/jobs/onceoff/onceoff.rb:35:in `execute'
/var/www/discourse/app/jobs/base.rb:316:in `block (2 levels) in perform'
rails_multisite-6.1.0/lib/rails_multisite/connection_management/null_instance.rb:49:in `with_connection'
rails_multisite-6.1.0/lib/rails_multisite/connection_management.rb:21:in `with_connection'
/var/www/discourse/app/jobs/base.rb:303:in `block in perform'
/var/www/discourse/app/jobs/base.rb:299:in `each'
/var/www/discourse/app/jobs/base.rb:299:in `perform'
sidekiq-6.5.12/lib/sidekiq/processor.rb:202:in `execute_job'
sidekiq-6.5.12/lib/sidekiq/processor.rb:170:in `block (2 levels) in process'
sidekiq-6.5.12/lib/sidekiq/middleware/chain.rb:177:in `block in invoke'
/var/www/discourse/lib/sidekiq/pausable.rb:132:in `call'
sidekiq-6.5.12/lib/sidekiq/middleware/chain.rb:179:in `block in invoke'
sidekiq-6.5.12/lib/sidekiq/middleware/chain.rb:182:in `invoke'
sidekiq-6.5.12/lib/sidekiq/processor.rb:169:in `block in process'
sidekiq-6.5.12/lib/sidekiq/processor.rb:136:in `block (6 levels) in dispatch'
sidekiq-6.5.12/lib/sidekiq/job_retry.rb:113:in `local'
sidekiq-6.5.12/lib/sidekiq/processor.rb:135:in `block (5 levels) in dispatch'
sidekiq-6.5.12/lib/sidekiq.rb:44:in `block in <module:Sidekiq>'
sidekiq-6.5.12/lib/sidekiq/processor.rb:131:in `block (4 levels) in dispatch'
sidekiq-6.5.12/lib/sidekiq/processor.rb:263:in `stats'
sidekiq-6.5.12/lib/sidekiq/processor.rb:126:in `block (3 levels) in dispatch'
sidekiq-6.5.12/lib/sidekiq/job_logger.rb:13:in `call'
sidekiq-6.5.12/lib/sidekiq/processor.rb:125:in `block (2 levels) in dispatch'
sidekiq-6.5.12/lib/sidekiq/job_retry.rb:80:in `global'
sidekiq-6.5.12/lib/sidekiq/processor.rb:124:in `block in dispatch'
sidekiq-6.5.12/lib/sidekiq/job_logger.rb:39:in `prepare'
sidekiq-6.5.12/lib/sidekiq/processor.rb:123:in `dispatch'
sidekiq-6.5.12/lib/sidekiq/processor.rb:168:in `process'
sidekiq-6.5.12/lib/sidekiq/processor.rb:78:in `process_one'
sidekiq-6.5.12/lib/sidekiq/processor.rb:68:in `run'
sidekiq-6.5.12/lib/sidekiq/component.rb:8:in `watchdog'
sidekiq-6.5.12/lib/sidekiq/component.rb:17:in `block in safe_thread'

Anyone any advice on how next to debug and proceed?