Veeam 13 issues after upgrade

[jcofin13]

WE upgraded to 13 2 days ago. It went well with no issues

That night the jobs ran and about 1/2 of the vms failed and continue to fail.

Case: 08020903


The vms that fail in the jobs show as follows:

Failed to prepare guest for hot backup. Error: Failed to connect to the guest OS.
Error: Failed to connect to the guest OS.
Processing finished with errors at 3/13/2026 11:12:04 AM

The application aware processing network and creds check says success but it shows connecting to the guest OS fails.

The ones where the backup actually works i show both the windows veeam installer agent on and the veeam agent installed. On the ones that are failing it is not.

I tried to take the VeeamInstallerSVC.exe from the vbr server and run it on the remote servers thinking that would install the 2 services that appear to be missing but no luck.

This shows in the event log:
Product: Veeam Installer Service -- Error 1722. There is a problem with this Windows Installer package. A program run as part of the setup did not finish as expected. Contact your support personnel or package vendor. Action ThirdPartyCheck, location: C:\Windows\Installer\MSI4DF5.tmp, command: /cancel


Veeam and the vms are on the same l2 network, win firewall is off, nothing is blocking that we can see.

All this worked before 13 with no issues for years.

The job takes MUCH longer to run now as each vm times out on this error. I have had a job running for about 13 hours and its almost done. Normally its an hour or two.

It would very much seem to be related to the application aware processing and these 2 services but thats all i got.

Ive had a case open for a bit but dont seem to be getting anywhere. Ive requested an update and have asked about several things but haven't gotten a response in almost 24 hours. I cant have these jobs failing into the weekend as it affects a very large portion of the production SQL data and probably 30+servers across multiple jobs in this instance.

Vmware 8 hosts/vms.

Can anyone provide any ideas as to what is going on here? It has to be something simple. I just cant seem to locate the issue.

[david.domask]

Hi jcofin13,

Sorry to hear about the challenges.

First, if there are concerns on the case processing / handling, please use the Talk to a Manager button in the case portal. This will connect you with Support Management, who will review the case and allocate additional resources as required.

Unfortunately will not be able to meaningfully comment on the behaviors you're describing here on the forums; the issue will require investigation of the debug logs, so please do continue with Veeam Support.

[Rydqvist]

After upgrading 13.0.1.1071 to 13.0.1.2067 last week, all my Windows VM´s fails with:
"Failed : Failed to prepare guest for hot backup. Error: Failed to establish connection because the guest agent is unavailable."

Test of credentials returns ok.

Maybe something similar?

Case #08021428

[jcofin13]

It was veeam/VBR not installing the Agent and Installer service or upgrading it from what i could tell. No idea why.

Was directed to do this Deployment Kit batch file: https://helpcenter.veeam.com/docs/vbr/u ... tml?ver=13
Running that batch file on every vm that was failing and then retrying the job on the failed vms seems to have worked.
Installing the msi installer directly for the guest services did not work. The batch file from the deployment kit did.

Kind of a mess for a few days but was able to get through it.

[david.domask]

Thanks for the update jcofin13 -- v13 indeed does switch from the .msi installer to Deployment Kits, so the solution makes sense here.

[newmrac]

Also have this issue after upgrading from December 2025 to the March 2026 build of VBR13, all PVE VMs fail to backup.
Case #08023330

[renatorichina]

Same issue here after upgrading last friday from 13.0.1.1071 to 13.0.1.2067. VM's running on Nutanix in our case : Case #08022476

[gasherbrum]

Same here on PVE Case #08024588 - only after updating to latest version released last week ones with guest processing fail

[david.domask]

@newmrac
@renatorichina
@gasherbrum

Please continue with Support -- the case from the topic creator saw progress by redeploying the Deployment Kits, and I can see in some of the cases Veeam Support advised this as well. Please continue with Veeam Support and follow the suggestions regarding the deployment kit.

For those who upgraded to the most recent Veeam patch, I will check internally if there are known issues, but not aware of any such issues at this time. I will update once I have more information.

[gasherbrum]

I have a windows based VBR and the deployment kit does not work for me, there is no checkbox to use persistent guest agent in the windows based VBR for guest processing. Veeam support is suggesting I change the job type to agent-based (lol). I would urge others to not upgrade to this patch if they use guest processing, as it seems to affect multiple hypervisors and this is breaking a major feature. Case #08024588

[Rydqvist]

To make it a little more complicated:
In my small test/dev-environment running VBR 13, I also run a Patchmanager-system.
The VBR-server is a client and another Windows-server in the domain is the patch-server.
After upgrading the VBR-server that is installed on the Active-Directory-server (bad bad, but this is test/dev only),
the Patchmanager-system also lost contact with all its Windows-clients, while Linux continue running fine.
I´m thinking if it is possible that upgrading VBR on the AD-server, broke/changed something affecting the whole domain.

Case #08021428

[david.domask]

gashebrum,

Thanks for the update; regarding the case, if you believe the case is off course, use the Talk to a Manager button from the case portal to contact Support Management; they will review the situation and allocate additional resources as needed on the case.

Discussing internally regarding Proxmox and Nutanix, no known issues have been reported outside of this thread so please continue with Veeam Support, if necessary the case will be escalated for further review to understand the root cause. Agreed that switching to Veeam Agent for the backups is not the correct method, but seems further investigation is required.

Rydqvist, understood, I see your support engineer has proposed a remote session and will review the situation in more detail. If necessary, case will be escalated for root cause analysis.

[gasherbrum]

Thanks David

I also have a VMWare 8 job with guest processing configured with the same VBR host/repo, it is currently working, so it appears to be isolated to guest processing w/ Proxmox.
Case #08024588

[newmrac]

I tried with installation of Deployment kit on all VMs. Not helped, still all backups fail with
16/03/2026 18:43:20 Failed : Failed to prepare guest for hot backup. Error: Cannot start service. Machine: [removed]. Service: [VeeamGuestHelper]. Cannot start service. Win32 error:The service did not respond to the start or control request in a timely fashion. Code: 1053
Also, after a fast initial response in the ticket 08023330, complete silence for >24 hours...
We have a lot of Proxmox 8 and 9 servers with VMs on them, all backups failing since update.\
I tried a full VBR reinstall, but it didn't help too.

[tyler.jurgens]

I strongly recommend everyone here keep working with support. The "Talk to a Manager" is a great way to escalate the ticket.

In the meantime, double check you have the latest version of the appropriate plugins (AHV/Proxmox).

The latest version for the Proxmox plugin is: 13.3.1.7
The latest version for the Nutanix plugin is: 13.9.1.11

[newmrac]

Yes, I have 13.3.1.7 PVE plugin installed.
I reinstalled the last VBR from scratch, but it didn't help.
I don't see what is "Talk to a manager", I see options with case only "Request Update" and "Request severity change". Since no answers for 2 days and P2 severity, I requested a change to P1, we lost the ability to do 90% of our backups

[renatorichina]

@newmrac
@renatorichina
@gasherbrum

Please continue with Support -- the case from the topic creator saw progress by redeploying the Deployment Kits, and I can see in some of the cases Veeam Support advised this as well. Please continue with Veeam Support and follow the suggestions regarding the deployment kit.

For those who upgraded to the most recent Veeam patch, I will check internally if there are known issues, but not aware of any such issues at this time. I will update once I have more information.

I've redeployed the Deployment Kit on all affected guest VM, VBR Servers, Guest proxy, according to instructions of the Veeam Support. But unfortuantely, the application aware backups still fail.

I am definitely sure, it is coming from Patch to Build 2067: before the patch installation, application aware backups with the persistent guest agent have worked, after the installation of the patch, the no longer do

[renatorichina]

I strongly recommend everyone here keep working with support. The "Talk to a Manager" is a great way to escalate the ticket.

In the meantime, double check you have the latest version of the appropriate plugins (AHV/Proxmox).

The latest version for the Proxmox plugin is: 13.3.1.7
The latest version for the Nutanix plugin is: 13.9.1.11

In KB4299, it's noted that Nutanix Plugin 13.9.1.11 is INCLUDED in VBR 13.0.1 P2, however in my case Nutanix plugin was still at version 13.9.0.212. So this seems to be either a wrong statement or there might be an issue with the upgrade process when installing the VBR 2067 Build Update.

So i've now manually upgraded the 13.9.1.11 Nutanix plugin. However, it doesn't solved the guest processing issue unfortunately. Just updating now the ticket

[daniel.lindner]

We are also facing an issue where the VeeamGuestHelper service fails to start.
I’m already in contact with Veeam Support to identify the root cause.
Currently, I can see that the GuestHelper service files are copied to the system and the service attempts to start, but immediately fails.

The service crashes and writes the following lines to the GuestHelper log:
[17.03.2026 10:03:23.294] < 7308> | Command line: C:\Windows\VeeamVssSupport\VeeamGuestHelper.exe -rpcPort -1
[17.03.2026 10:03:23.294] < 7308> | Writing dump. Dump path: C:\Windows\VeeamVssSupport\VSS_crash_0.mdmp.
[17.03.2026 10:03:23.400] < 7308> | Executing crash handlers.
[17.03.2026 10:03:23.400] < 7308> | Crash handlers were successfully executed.

Since the memory dump C:\Windows\VeeamVssSupport\VSS_crash_0.mdmp is deleted right after each failed attempt, I currently have no way to provide it to the support team along with the other collected information.
It seems that this Patch hasn't been tested enough

[magrichad]

Case: #08026088

After the latest update our Nutanix back-up jobs on Windows Servers editions are all failing with the following issue "Failed to install guest processing components". When we test guest processing credentials, it succeeds but the reaction speed goes between seconds to 1:30 min. This does not seem to be the failure cause directly, because the job is also failing on servers that succeed the test within 2-3 seconds.

Before this KB patch, everything was working fine. Prism central is 7.3.1.3.

[moderniste]

Case #08023199 [Moderator: Replaced Support Id with Case Number]
Hi,
same issue here.
Prism central is 7.3.1.3 and Nutanix AHV manual upgrade to 13.9.1.11 because upgrade 13.0.1.2067 didn't do.
Before 13.0.1.2067 all was fine.
I have same behavior with GuestHelper and support which not reply ...

[david.domask]

We are currently investigating the issue internally and will post an update once there is more information.

Appreciate everyone who has shared a case number, it is important for us to both track and validate that the observed behavior and also for more easily communicating a resolution once it's ready.

[daniel.lindner]

Our case number Case #08024166

[kpitt]

Add my case to the list please.

Case # 08022649

[JedTheHead]

Hi all!

Upgraded from VEEAM 12.x to the latest 13.x version to try to take advantage of the Guest Application Processing in VEEAM for our PVE VMs. Previously backups were working great, now getting the "Failed to prepare disks" error.

PVE Version: 9.1.1
VEEAM PVE Plugin Version: 13.3.1.7

Curious if anyone else is seeing this or has a fix.

Thanks!
Jed

[david.domask]

Hi @JedTheHead,

I've moved your post to an existing topic on the subject as it may match. Please see my previous post, we're researching this issue internally, and will update once we have more information.

Please open a Support Case for the behavior and share your case number once created. Support will review the behavior and confirm next steps, and if it's different behavior Support will assist with root cause analysis and resolution.

[JedTheHead]

Thank you!

Some additional information:
VEEAM version is 13.0.1.2067
PVE Version: 9.1.1
VEEAM PVE Plugin Version: 13.3.1.7

VEEAM is running on a physical host, Windows Server 2016 (Datacenter)
The VMs I am testing with are both Windows Server 2016 (Datacenter)

- I am using network storage for the VM snapshots (same location as the datastore). I have tried local storage and received the same error.
- I have tried changing the VM machine type to 9.2 and 9.2+pve as seen in some posts. Same error.
- I have removed and re-deployed the workers / proxies after / since the upgrade to 13.x. Same error.
- All tests of proxies pass with no errors.

*** IMPORTANT: If I disable Guest Processing altogether in the backup job, it completes successfully. I have tied just "Application aware processing" and "Guest file system indexing...." individually and either of them cause the job to fail.

Please let me know if I can provide additional information (and specific log file locations if needed.)

[david.domask]

Thanks for all that Jeff, but please open a Support Case as requested Based on your extended description it looks to match, but Support will need to confirm from the logs, and if there is a fix created, it will be distributed through support.

Issue is still under investigation, everyone's patience is appreciated, and will post an update here once we have more information to share.

[JedTheHead]

Thanks all! Case opened.

Another observation for the good of the group (and shared with support): When using the Help > Support Information to export logs, PVE VM jobs do not show in the list of Jobs to choose from when exporting logs. All other jobs do. I chose to export all logs from the last three days instead.

Thanks!
Jed

[GreenEnvy]

I will open a case tomorrow, but we're seeing the same thing in our environment.
Proxmox 9, backups were working fine until we upgraded Veeam from 13.0.1.1071 to 13.0.1.2067, via the patch.
Now any Windows VM (mix of 2022 and 2025) with application aware processing fails, even though the precheck passes.
This is 2 sites for us, basically identical, but one site Veeam is running on a VM in the same proxmox cluster, while the other site has Veeam running on a dedicated Windows server.
Proxmox vm's are stored on a Starwind vSan, Veeam workers are on an NFS datastore.