My Windows Server (2022 Standard) client yesterday made its first backup to my UrBackup server running as a Docker app (App Version 2.5.x, Version 1.1.6) on my NAS running TrueNAS 25.10.7. This morning it doesn’t see the server anymore:
“Server unreachable.”
When I try to trigger a new incremental backup from the pull-down on the Status page of the UrBackup GUI, it says, “Starting backup failed.”
What could have changed?
Maybe the urbackup client service on your client stopped/isn’t running?
Or a firewall for the required communication ports is closed/preventing communication?
In the gui for urbackup admin, under the specific client, schedule times/days?
Have you marked this client as local or internet?
What (if any) do the logs - probably more info at client end - say?
In my experience, it’s usually more something at the client end that prevents the server from “seeing” the client. Things like “internet enabled” not set to yes, the communication port not set, the name of IP of the server not set/incorrect.
Plus (I know this sounds silly/obvious) how long was the client “up” before checking on status page in gui to see if it is present?
The more specific details you give, the more likely someone can help.
Dave
Hi Dave! I really appreciate your suggestions!
The services is running:
A firewall does not come into play, as both the server and the client are on the same local subnet.
The client has not shown up on the Backup Status page.
On the Internet tab of the client settings “Enable backup via internet” is not checked.
Here are the contents of the file debug.log from right after I restarted the UrBackup service in the Services utility:
2026-09-10 14:59:23: Loaded -fileserv- plugin
2026-09-10 14:59:23: Loaded -fsimageplugin- plugin
2026-09-10 14:59:23: Loaded -cryptoplugin- plugin
2026-09-10 14:59:23: SQLite: recovered 24 frames from WAL file C:\Program Files\UrBackup\urbackup\backup_client.db-wal code: 283
2026-09-10 14:59:23: FileSrv: Backup privileges set successfully
2026-09-10 14:59:23: FileSrv: Backup privileges set successfully (SE_SECURITY_NAME)
2026-09-10 14:59:23: FileSrv: Backup privileges set successfully (SE_RESTORE_NAME)
2026-09-10 14:59:23: urbackupserver: Server started up successfully!
2026-09-10 14:59:23: FileSrv: Binding UDP socket at port 35622...
2026-09-10 14:59:23: FileSrv: done.
2026-09-10 14:59:23: FileSrv: Disabling new behavior...
2026-09-10 14:59:23: FileSrv: Binding ipv6 UDP socket at port 35622...
2026-09-10 14:59:23: sambaredir: Server started up successfully!
2026-09-10 14:59:23: FileSrv: done.
2026-09-10 14:59:23: FileSrv: Disabling new behavior...
2026-09-10 14:59:23: FileSrv: Servername: -WinServer-
2026-09-10 14:59:23: FileSrv: Server started up successfully
2026-09-10 14:59:23: Started UrBackupClient Backend...
2026-09-10 14:59:23: FileSrv: UDP Thread started
2026-09-10 14:59:23: Filesystem. Vol="\\?\Volume{5e6dbc70-e2b5-42d3-9718-e01e7f47ccca}\" Name="" Type="ntfs" VPaths=1 Size=511436648448
2026-09-10 14:59:23: Filesystem is System partition. Skipping...
2026-09-10 14:59:23: Filesystem. Vol="\\?\Volume{f7880359-e210-44c1-a619-2884d51cf3d4}\" Name="" Type="ntfs" VPaths=0 Size=549449728
2026-09-10 14:59:23: GPT formated hard disk encountered. No bootable flag. Attributes = -9223372036854775807
2026-09-10 14:59:23: Do not automount is set
2026-09-10 14:59:23: System partition is set
2026-09-10 14:59:23: Bootable flag set for volume
2026-09-10 14:59:23: Found potential candidate: \\?\Volume{f7880359-e210-44c1-a619-2884d51cf3d4}\ Score: 3
2026-09-10 14:59:23: Filesystem. Vol="\\?\Volume{de96ecb7-bb61-4b71-a599-ce1c4a751b6e}\" Name="" Type="fat32" VPaths=0 Size=100663296
2026-09-10 14:59:23: GPT formated hard disk encountered. No bootable flag. Attributes = -9223372036854775808
2026-09-10 14:59:23: Do not automount is set
2026-09-10 14:59:23: Bootable flag not set for volume
2026-09-10 14:59:23: Found potential candidate: \\?\Volume{de96ecb7-bb61-4b71-a599-ce1c4a751b6e}\ Score: 3
2026-09-10 14:59:23: Filesystem. Vol="\\?\Volume{8fc1db15-c154-11ef-9bee-806e6f6e6963}\" Name="" Type="" VPaths=1 Size=-1
2026-09-10 14:59:23: GetVolumeInformation failed with error code 21. Skipping...
2026-09-10 14:59:23: Selected volume \\?\Volume{f7880359-e210-44c1-a619-2884d51cf3d4}
2026-09-10 14:59:23: System dir: C:\Windows
2026-09-10 14:59:23: Volpath: \\.\C:
2026-09-10 14:59:23: EFI partition with type UUID {C12A7328-F81F-11D2-BA4B-00A0C93EC93B}
2026-09-10 14:59:23: EFI System Partition is at \\?\GLOBALROOT\Device\Harddisk0\Partition1
2026-09-10 14:59:23: urbackupserver: No available slots... starting new Worker
2026-09-10 14:59:23: ClientService cmd: STATUS#pw=******************************
2026-09-10 14:59:23: ClientService cmd: STATUS DETAIL#pw=******************************
2026-09-10 14:59:24: Internet mode not enabled
2026-09-10 14:59:24: Looking for old Sessions... 0 sessions
This is followed by many lines looking like this:
2026-09-10 14:59:23: ClientService cmd: STATUS DETAIL#pw=******************************
… one of them every second.
I do not see a smoking gun in that log file. Is there somewhere else I can look?
The client has been up for 35 min since I restarted the UrBackup service on the client.
My personal (incredibly frustrating) experience(s) have been that, invariably, it is the CLIENT that is the issue.
SO.
To say that no firewall is in play (due to both being on local lan) does not imply that there isn’t a firewall program/app running on either machine.
You haven’t mentioned the Client’s O/S and version. It would be helpful to know as different O/S clients place config/logs in different locations.
For windows servers and clients I would, temporarily, disable firewall service completely. Thus ensuring,despite your protestations, that no firewall is running.
I have one client in my setup which, for reasons I cannot be bothered to determine, refuses to work unless it is marked in the server (and the client) as being an internet client.
When I examine the client log - on the client - it always says “Internet not enabled” or words to that effect. That is; whether or not I have told the server (in the gui) that this client is internet. SO - I then set the server gui for this client to internet - and copy the associated key/code. Then I go to the client and locate (with difficulty) the config file and ensure the port, server name, key, blah blah are all set. Stop the client service for at least 5 minutes. Then restart, say “there’s no place like home” and hope.
Watch the client log. Best is to edit it, empty it and then watch it.
The client background service also can (on some O/S’s) -state immediately on startup, if there is a problem with the config… often frustrating.
Have you got another working client - same O/S which you can look at?
Did you try using the download client option in the server gui to get a “pre-configured” client setup binary?
The screenshots you supplied for the server are great. But, as I say, perhaps more details of the client settings would be additionally useful.
Don’t give up hope. It really is a great, reliable program - once set.
Last - I know it’s bleedin obvious but - what schedule in the gui have you set?
I am awake at odd hours in the UK - so, feel free to reply at any old time.
Dave
Thanks, Dave!
I just turned all those off.
The problem may be that, as can be seen above, the “private networks” are not connected. I don’t know enough about Windows Server, but if a Windows Server box creates an implicit city wall around the domain it hosts, then that may be the problem. Maybe I have to turn off the domain controller.
I installed a brand-new mini PC with Windows 11 Pro on it now (26200.9445). I was being impatient; rather than waiting to see, whether it would get picked up by the server I added it by hitting the “Add new client” button. This time, for the first time I entered the LAN IP address of the client here:
And it just started backing up. I did the same with my Windows Server box, and, lo and behold, it too began being backed up.
It is a solution for my situation, but still begs the question, why it does not work automatically without adding a client discovery hint and, why it does not work, when the hint is simply the Windows computer name.
As of now my Windows Server box dropped of the UrBackup server’s list of online computers:
I have no idea, what happened between 9:26 PM yesterday and today.
Incidentally, the BosGame PC, the first one in the list above was assigned a new IP address through DHCP. I have not assigned it a static DHCP IP address. Maybe the backup server will pick it up eventually. I will wait and see.
In Chapter 5 (“Client discovery in local area networks”) of the manual I read that the server sends out a broadcast packet to the subnet, to which the client responds with its fully-qualified domain name (FQDN). Could it be that there has to be a correspondence between the FQDN and the name set on Client tab of the client’s settings?
I changed that name to match the hostname part of the FQDN and added that to the list of client discovery hints. The server now recognizes that host to be online. However, it has not yet attempted to back it up.
Some users of this forum might find my seemingly endless stream of posts annoying, but I view it more like a blog of what my troubleshooting steps are, which will hopefully end with a description of a solution that might help others in a similar situation. UrBackup, when it works, is a great backup solution, which, because it’s freeware, can save users a lot of money.
So, my Windows Server box again is not backing up:
In the second column (“Online”) it says, “No.”
Yet, when I enter the name through the “+ Add new client” button and see it in the Client discovery hints it shows online:
I know this has nothing to do with the host being a Windows Server host, as I have another Mini PC running the latest version of Windows 11 (26200.9445), which shows the same symptoms.
Some aspect of the server-client communication is breaking down. Obviously! I wish I could figure out, how to troubleshoot this.
Taking another look at logs…
I turned on debug mode by running the batch file enable_debug_logging.bat in the UrBackup directory (C:\Program Files\UrBackup).
The debug.log file shows lots of entries like this:
2026-09-14 06:17:54: WARNING: Parent directory not found in MFT. Was probably deleted.
2026-09-14 06:17:54: WARNING: Parent of file with FRN 1970324837301235 (Name "000700000004FBF347A9C323") with FRN 281474976710685 not found. Searching via MFT as fallback.
Not sure, what this means, how to fix this, or whether fixing this will allow backups to resume.
Hey.
The message about the M.aster F.ile T.able file not found is a WARNING. Urbackup will continue despite warnings.
I’d like to know whether you are using file backup, image backup or both.
Also, if file backup, what paths have you chosen to backup, what (if any exclusions etc). A print screen of that page for the client that works and also for the one that doesn’t. May(??) reveal something.
Personally, I find the multiple messages/blog format more useful as, when there can be multiple diagnostics and corresponding attempts to solve… they are more easily followed/compartmentalized. Whereas a huge email string of connected messages can be more confusing.
Ps - are you using docker for the urbackup server?
Dave
I am trying to do both. Would it make a difference? How would that affect server-client communication from the get-go?
The one that is working is a remote client. From the verbiage used in the UrBackup sever UI, one is passive (the one on the local subnet) the other active, because it initiates the connection from outside of the local network. So, in other words, two totally different scenarios.
I think, these are the default exclusions (copied from the File backups tab of the client settings):
C:\ProgramData\Microsoft\Network\Downloader\*;C:\WINDOWS\system32\LogFiles\WMI\RtBackup\:.:;C:\Users\admin\index.dat;C:\WINDOWS\Minidump\*;:\Pagefile.sys;:\System Volume Information\MountPointManagerRemoteDatabase;C:\Windows\System32\MSDTC\MSDTC.Log;C:\WINDOWS\netlogon.chg;:\hiberfil.sys;:\System Volume Information\Heat\*.*;C:\Users\admin\AppData\Local\Temp\*;:\System Volume Information\*{3808876B-C176-4e48-B7AE-04046E6CC752};:\System Volume Information\:.{7cc467ef-6865-4831-853f-2a4817fd1bca}ALT;:\System Volume Information\:.{7cc467ef-6865-4831-853f-2a4817fd1bca}DB;C:\ProgramData\Microsoft\Windows\WER\*;C:\WINDOWS\softwaredistribution\*.*;:\System Volume Information\FVE2.{e40ad34d-dae9-4bc7-95bd-b16218c10f72}.:;:\System Volume Information\FVE2.{c9ca54a3-6983-46b7-8684-a7e5e23499e3};:\System Volume Information\FVE2.{24e6f0ae-6a00-4f73-984b-75ce9942852d};:\System Volume Information\FVE2.{9ef82dfa-1239-4a30-83e6-3b3e9b8fed08};:\System Volume Information\FVE2.{aff97bac-a69b-45da-aba1-2cfbce434750}.:;:\System Volume Information\FVE2.{9ef82dfa-1239-4a30-83e6-3b3e9b8fed08}.:;:\System Volume Information\FVE.{e40ad34d-dae9-4bc7-95bd-b16218c10f72}.:;:\System Volume Information\FVE.{c9ca54a3-6983-46b7-8684-a7e5e23499e3};:\System Volume Information\FVE.{9ef82dfa-1239-4a30-83e6-3b3e9b8fed08};C:\Users\:\AppData\Local\Temp;C:\Users\:\AppData\Local\Microsoft\Windows\Temporary Internet Files;C:\Users\:\AppData\Local\Google\Chrome\User Data\Default\Cache;C:\Users\:\AppData\Local\Google\Chrome\User Data\Default\Media Cache;C:\Users\:\AppData\Local\Google\Chrome\User Data\Default\Code Cache;C:\Users\:\AppData\Local\Microsoft\Windows\Explorer\thumbcache*;C:\Users\:\AppData\Local\Microsoft\Terminal Server Client\Cache;C:\Users\:\AppData\Local\Mozilla\Firefox\Profiles\:\cache2;C:\Users\:\AppData\Local\Mozilla\Firefox\Profiles\:\cache;C:\Windows\Temp;:\$Recycle.Bin;:\System Volume Information;C:\Windows.old;C:\$Windows.~BT;C:\ProgramData\Microsoft\Windows Defender\Scans\mpcache-*;C:\Windows;C:\$GetCurrent;C:\Program Files;C:\Program Files (x86);C:\ProgramData
I agree. However, this one is still dealing with the one issue of the local client not being recognized by the server.
Yes. It’s the Docker UrBackup server app running on TrueNAS.
Would it make a difference if doing both? - No.
I think I may have been unclear about the printscreen.
I wish to see the Web Gui of the Server’s Client settings including the line at the bottom showing the version of the server.
Both working client settings and non-working client settings as shown in the web gui.
Why? because the connection is instigated by the server.
According to you, the remote client is doing an ad-hoc connection. Whereas the (non-working) is expecting to receive and respond to the server broadcast.
Specifically for Client good I want screen dumps of the following tabs;
FIle backups, image Backups, Permissions, Local/Passive, Internet/Active.
Ditto for client Bad.
I know this is a lot and I apologise.
But, in my experience, the more detail available; perhaps an alternate set of eyes might discover something overlooked.
Yes, two totally different scenario’s. But, I guess you don’t mind if we make one pretend to be that which it is not and it then works?
David