service/forum.md

@@ -164,6 +164,8 @@ https://meta.discourse.org/t/partial-read-only-mode/210401/18
 
 ## Pager playbook
 
+### Email issues
+
 If mail is not going out or some recurring background job doesn't
 work, see the Sidekiq dashboard in:
 
@@ -174,6 +176,18 @@ able to see those failures in:
 
 <https://forum.torproject.org/sidekiq/retries>
 
+### Upgrade failure
+
+When upgrading using the web interface, it's possible for the process to fail
+with a `Docker Manager: FAILED TO UPGRADE` message in the logs.
+
+The quickest way to recover from this is to rebuild the container from the
+command-line:
+
+     cd /srv/discourse
+     git pull
+     ./launcher rebuild app
+
 ## Disaster recovery
 
 In case the machine is lost, it's possible to restore the forum from backups.