# Running multisite:migrate concurrently fails

**URL:** https://meta.discourse.org/t/running-multisite-migrate-concurrently-fails/397755
**Category:** Bug
**Created:** [March 5, 2026, 4:27pm UTC](https://meta.discourse.org/t/running-multisite-migrate-concurrently-fails/397755 "2026-03-05T16:27:13Z")
**Posts on this page:** 1
**Showing post:** 1

<div class="post-metadata">

### Author: ![RGJ](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/rgj/32/523185_2.png) [@RGJ](https://meta.discourse.org/u/RGJ)
#### Post date: [March 5, 2026, 4:27pm UTC](https://meta.discourse.org/t/running-multisite-migrate-concurrently-fails/397755/1 "2026-03-05T16:27:13Z")

</div>

Related to [this](https://github.com/discourse/discourse/commit/790dc4a5ed16a7ef146bfe2cd1d218239d007c58), I guess

```plaintext
Multisite migrator is running using 2 processes
Running migrations and seeds for default database(s)
[mutex.cc : 2443] RAW: Check w->waitp->cond == nullptr failed: Mutex::Fer while waiting on Condition
rake aborted!
Parallel::DeadWorker: Parallel::DeadWorker (Parallel::DeadWorker)
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:83:in 'Parallel::Worker#work'
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:545:in 'block (4 levels) in Parallel.work_in_processe
s' 
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:660:in 'Parallel.with_instrumentation'
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:544:in 'block (3 levels) in Parallel.work_in_processe
s' 
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:532:in 'block (2 levels) in Parallel.work_in_processe
s' 
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:219:in 'block (4 levels) in Parallel.in_threads'

Caused by:
EOFError: end of file reached (EOFError)
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:81:in 'Parallel::Worker#work'
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:545:in 'block (4 levels) in Parallel.work_in_processe
s' 
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:660:in 'Parallel.with_instrumentation'
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:544:in 'block (3 levels) in Parallel.work_in_processe
s' /var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:532:in 'block (2 levels) in Parallel.work_in_processe
s'
/var/www/discourse/vendor/bundle/ruby/3.4.0/gems/parallel-1.27.0/lib/parallel.rb:219:in 'block (4 levels) in Parallel.in_threads'
Tasks: TOP => multisite:migrate
(See full trace by running task with --trace)
Migration failed --> RC = 1 

```

---

_[View the full topic](https://meta.discourse.org/t/running-multisite-migrate-concurrently-fails/397755)._