diff --git a/howto/backup.md b/howto/backup.md
index 1d7db177c7219fa872ca90676d340c51a33ac84c..7a25b2eadd3ed4a9ce6c5651fe0686876be4603f 100644
--- a/howto/backup.md
+++ b/howto/backup.md
@@ -791,6 +791,44 @@ resolved the problem and the warning went away. It is assumed the
 problem will not return on the next job run. See [issue 40110](https://gitlab.torproject.org/tpo/tpa/team/-/issues/40110) for
 one example of this problem.
 
+### Bacula GDB traceback / Connection refused / Cannot assign requested address: Retrying
+
+If you get an email from the directory stating that it can't connect
+to the file server on a machine:
+
+    09-Mar 04:45 bacula-director-01.torproject.org-dir JobId 154835: Fatal error: bsockcore.c:209 Unable to connect to Client: scw-arm-par-01.torproject.org-fd on scw-arm-par-01.torproject.org:9102. ERR=Connection refused
+
+You can even receive an error like this:
+
+> root@forrestii.torproject.org (1 mins. ago) (rapports root tor)
+> Subject: Bacula GDB traceback of bacula-fd on forrestii
+> To: root@forrestii.torproject.org
+> Date: Thu, 26 Mar 2020 00:31:44 +0000
+>
+> /usr/sbin/btraceback: 60: /usr/sbin/btraceback: gdb: not found
+
+In any case, go on the affected server (in the first case,
+`scw-arm-par-01.torproject.org`) and look at the `bacula-fd.service`:
+
+    service bacula-fd status
+
+If you see an error like:
+
+    Warning: Cannot bind port 9102: ERR=Cannot assign requested address: Retrying ...
+
+It's Bacula that's being a bit silly and failing to bind on the
+external interface. It might be an incorrect `/etc/hosts`. This
+particularly happens "in the cloud", where IP addresses are in the
+RFC1918 space and change unpredictably.
+
+In the above case, it was simply a matter of adding the IPv4 and IPv6
+addresses to `/etc/hosts`, and restarting bacula-fd:
+
+    vi /etc/hosts
+    service bacula-fd restart
+
+The GDB errors were documented in [issue 33732](https://gitlab.torproject.org/tpo/tpa/team/-/issues/33732).
+
 ## Disaster recovery
 
 <a name="Restoring-the-directory-server"></a>