After upgrading to v2026.3.0 my instance fails to bootstrap with this error:
/var/www/discourse/plugins/discourse-subscriptions/plugin.rb:53:
uninitialized constant Plugin::Instance::USERNAME_ROUTE_FORMAT (NameError)
The USERNAME_ROUTE_FORMAT constant appears to have been removed in this version and discourse-subscriptions still references it at line 53.
Worth noting — the error is misleading. The stack trace implicates whichever plugin calls routes.draw first rather than discourse-subscriptions directly, which makes it easy to spend time debugging the wrong plugin.
Yes I’m using the official install via discourse_docker on Ubuntu 24.04.
The error reproduces consistently on v2026.3.0-latest. The constant is not defined at the point discourse-subscriptions loads during route finalization, which suggests a load ordering issue rather than the constant being absent from core entirely.