Bacula fatal error backing up a Trixie node: "Bad caps from SD: auth cram-md5"

We're getting errors like this over email:

10-Apr 23:39 bacula-director-01.torproject.org-dir JobId 297683: Start Backup JobId 297683, Job=idle-dal-03.torproject.org.2025-04-10_23.39.44_56
10-Apr 23:39 bacula-director-01.torproject.org-dir JobId 297683: Using Device "FileStorage-idle-dal-03.torproject.org" to write.
10-Apr 23:39 idle-dal-03.torproject.org-fd JobId 297683: Fatal error: hello.c:191 Bad caps from SD: auth cram-md5 <1789412574.1744328389@bungei.torproject.org-sd> ssl=2.
10-Apr 23:39 bacula-director-01.torproject.org-dir JobId 297683: Fatal error: Bad response to Storage command: wanted 2000 OK storage, got 2800 End Job TermCode=102 JobFiles=0 ReadBytes=0 JobBytes=0 Errors=1 VSS=0 Encrypt=0 CommBytes=87 CompressCommBytes=87
10-Apr 23:39 bacula-director-01.torproject.org-dir JobId 297683: Fatal error: No Job status returned from FD.
10-Apr 23:39 bacula-director-01.torproject.org-dir JobId 297683: Error: Bacula bacula-director-01.torproject.org-dir 9.6.7 (10Dec20):
  Build OS:               x86_64-pc-linux-gnu debian bookworm/sid
  JobId:                  297683
  Job:                    idle-dal-03.torproject.org.2025-04-10_23.39.44_56
  Backup Level:           Full
  Client:                 "idle-dal-03.torproject.org-fd" 15.0.3 (25Mar25) x86_64-pc-linux-gnu,debian,trixie/sid;bpipe(2)
  FileSet:                "Standard Set" 2014-09-06 20:30:19
  Pool:                   "poolfull-torproject-idle-dal-03.torproject.org" (From Job resource)
  Catalog:                "MyCatalog" (From Client resource)
  Storage:                "File-idle-dal-03.torproject.org" (From Pool resource)
  Scheduled time:         10-Apr-2025 23:39:44
  Start time:             10-Apr-2025 23:39:46
  End time:               10-Apr-2025 23:39:49
  Elapsed time:           3 secs
  Priority:               10
  FD Files Written:       0
  SD Files Written:       0
  FD Bytes Written:       0 (0 B)
  SD Bytes Written:       0 (0 B)
  Rate:                   0.0 KB/s
  Software Compression:   None
  Comm Line Compression:  None
  Snapshot/VSS:           no
  Encryption:             no
  Accurate:               yes
  Volume name(s):         
  Volume Session Id:      328
  Volume Session Time:    1744055054
  Last Volume Bytes:      0 (0 B)
  Non-fatal FD errors:    1
  SD Errors:              0
  FD termination status:  Error
  SD termination status:  Waiting on FD
  Termination:            *** Backup Error ***