Error when backup

What version of Veeam 12 are you running?  What operation are you trying to run when the error happens.  We need more details otherwise we are just guessing.

Please add as much detail to get some guidance as we are not technical support but can help as best we can.

error occurs when I run backup jobs on hyper v virtualized servers

Hi @DuongIT 

as Chris wrote we are not official support, and anyway they'd ask you the logs. 

To reply to your issue we need to have more and more info. 

Probably your Hyper-V host is not detected but we cannot doing any troubleshooting. 

Let us know how we can help you.

Can you reach the servers HyperV properly ?
Do you have right config DNS ?
@DuongIT You need to be more detailed in your infrastructure information….

I can still access normally, the error only happened yesterday, before that the backup jobs were still normal

I think you have already checked to see if any Windows Updates have been made on the disputed servers... including DNS configured on the Veeam server's nic.

Is there any way for tasks to run normally?

are your Hyper-V servers configured in a failover cluster?

Its possible they have failed over but the backup job is configured via the host rather than the cluster.

Is there any way for tasks to run normally?

Yes when a job runs it is normal. Based on your issue you are better off opening a support ticket and working with them. We still need a lot more information on your environment and support can use the logs to get to an answer faster for you.

What version of Hyper-V are you using?  Is the server fully patched?  Is DNS working correctly?  Are the credentials being used correct and no expired password?

@DuongIT -

As Chris shared...we’re needing a bit more info to help you here.

1. Is there error you’re getting related to a “managed server” (i.e. a Veeam component such as Repository, Proxy, or other)? Or, is the error related to a VM you’re trying to backup?
2. Do you have any Veeam Components → Hyper-V, Repository, Proxy, etc which show as ‘unavailable’ in the Inventory node?
3. You can also check the Backup logs in: C:\ProgramData\Veeam\Backup\<job-name>.log to see if there is more detailed info there. 
4. Can you share any screenshots?
5. At the very least, as Chris shared, opening a Support ticket with Veeam will probably serve you best.

Any port changes as of recent or FW updates?

same over here…. no changes, and from one day to the other backup server is unavaliable

Doublecheck your Backup Target! Message was not clear for me too. My Backuptarget was a NAS that failled. Redirection of the Job to a different Target fixed the issue.
 

Same here! I had the same error message, and the situation was the same: the target NAS device was not accessible. Thanks masterase for the hint!

Veeam, come on! Fix your error messages! Why complain about the connection to the hyper-v server when the connection to the repo is down? 

I had this issue for last couple of days. We cloned a Veeam server, took down the original and began using the clone. The clone got a new ip address. Since backups were to a Synology NAS using NFS we had to add the veeam server ip to the nas NFS share to allow it to write to it. Problem solved.

When you get an ‘unavailable’ error, it typically happens due to connection issues, such as a host rebooting at the scheduled time. Sometimes, it can also be caused by a network issue, OS updates, permission problems, or other factors.

I have encountered many issues with Hyper-V, like UAC, IPV6, windows update, local policy, windows firewall, services not running and other. You should check if there were any changes in your environment before starting the troubleshooting process. Open Veeam and try to authenticate with the virtual infrastructure to see if you get a message like this:

Also, please try to provide more information as requested by ​@coolsport00 :