EthanH - I think I pretty much have an idea what's going on. But meantime, We can eliminate error 71. But am still curious reason for exit status 25. detailed status below.
To answer your question :
Exclude drive = M:\ ( This drive is shared by 2 systems in cluster. This is a mapped drive from vmax)
Client regularly get patched which hasn't cause any issue before
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Jun 10, 2020 1:40:27 AM - Info bpbrm (pid=219119) mickey is the host to backup data from
Jun 10, 2020 1:40:27 AM - Info bpbrm (pid=219119) reading file list for client
Jun 10, 2020 1:40:28 AM - Info bpbrm (pid=219119) accelerator enabled
Jun 10, 2020 1:40:32 AM - Info bpbrm (pid=219119) starting bpbkar on client
Jun 10, 2020 1:40:34 AM - Info bpbkar (pid=6576) Backup started
Jun 10, 2020 1:40:34 AM - Info bpbrm (pid=219119) bptm pid: 219247
Jun 10, 2020 1:40:34 AM - Info bpbkar (pid=6576) change time comparison:<enabled>
Jun 10, 2020 1:40:34 AM - Info bpbkar (pid=6576) accelerator enabled backup, archive bit processing:<disabled>
Jun 10, 2020 1:40:34 AM - Info bpbkar (pid=6576) not using change journal data for <M:\>: not supported for non-local volumes / file systems
Jun 10, 2020 1:40:34 AM - Info bptm (pid=219247) start
Jun 10, 2020 1:40:35 AM - Info bptm (pid=219247) using 262144 data buffer size
Jun 10, 2020 1:40:35 AM - Info bptm (pid=219247) using 30 data buffers
Jun 10, 2020 1:40:36 AM - Info bptm (pid=219247) start backup
Jun 10, 2020 1:40:43 AM - Info bpbrm (pid=219119) from client mickey: TRV - object not found for file system backup: M:
Jun 10, 2020 1:40:44 AM - Info bpbkar (pid=6576) accelerator sent 2048 bytes out of 2048 bytes to server, optimization 0.0%
Jun 10, 2020 1:40:44 AM - Error bptm (pid=219247) cannot add fragment to image database, error = cannot connect on socket
Jun 10, 2020 1:40:45 AM - Info bptm (pid=219247) EXITING with status 25 <----------
Jun 10, 2020 1:40:45 AM - Info mouse (pid=219247) StorageServer=PureDisk:mouse; Report=PDDO Stats for (mouse): scanned: 3 KB, CR sent: 0 KB, CR sent over FC: 0 KB, dedup: 100.0%, cache disabled
Jun 10, 2020 1:40:45 AM - Error bpbrm (pid=219119) could not send server status message to client
Jun 10, 2020 1:40:46 AM - Info bpbkar (pid=6576) done. status: 25: cannot connect on socket
Jun 10, 2020 1:48:23 AM - Info nbjm (pid=25361) starting backup job (jobid=12992158) for client mickey, policy mouse_windows_2AM_Gold_v1, schedule mouse_Incremental_Daily
Jun 10, 2020 1:48:23 AM - Info nbjm (pid=25361) requesting STANDARD_RESOURCE resources from RB for backup job (jobid=12992158, request id:{FEF7858C-AADD-11EA-A0AF-4ABA3473E158})
Jun 10, 2020 1:48:23 AM - requesting resource stu_disk_mouse
Jun 10, 2020 1:48:23 AM - requesting resource xyz.NBU_CLIENT.MAXJOBS.mickey
Jun 10, 2020 1:48:23 AM - granted resource xyz.NBU_CLIENT.MAXJOBS.mickey
Jun 10, 2020 1:48:23 AM - granted resource MediaID=@aaadw;DiskVolume=PureDiskVolume;DiskPool=dp_disk_mouse;Path=PureDiskVolume;StorageServer=mouse;MediaServer=mouse
Jun 10, 2020 1:48:23 AM - granted resource stu_disk_mouse
Jun 10, 2020 1:48:23 AM - estimated 0 kbytes needed
Jun 10, 2020 1:48:23 AM - Info nbjm (pid=25361) resumed backup (backupid=mickey_1591765395) job for client mickey, policy mouse_windows_2AM_Gold_v1, schedule mouse_Incremental_Daily on storage unit stu_disk_mouse
Jun 10, 2020 1:48:23 AM - started process bpbrm (pid=219119)
Jun 10, 2020 1:48:30 AM - connecting
Jun 10, 2020 1:48:31 AM - connected; connect time: 0:00:00
Jun 10, 2020 1:48:46 AM - end writing
cannot connect on socket (25)