KB5001347 (April 2021 Update): Issue with Server Backup on Hyper-V Server 2016

Question

Are there anyone else seeing issues with Windows Server Backup on Hyper-V Server 2016 after installing KB5001347? We can reliable reproduce failing backups at stage "system state".

After uninstalling KB5001347 backups run as expected again. After re-installing KB5001347 backups stop working again.

The error message(s) in backup management console is/are:

• The mounted backup volume is inaccessible. Please retry the operation.
• The operation ended before completion.

The following error(s) is/are logged in event viewer:

• 517, Backup: The backup operation that started at 'UTC‎TIMESTAMP' has failed with following error code '0x8078004F' (The mounted backup volume is inaccessible. Please retry the operation.). Please review the event details for a solution, and then rerun the backup operation once the issue is resolved.
• 10170, HYPER-V-VMMS: Requester reported unsuccessful backup for the virtual machine 'MACHINENAME'. (Virtual machine ID GUID).

Thank you in advance!

Answer 1

Hi,

Thank you for your reply!

Based on your descriptions, I suppose your issue may be more related to Synology product. For one thing, you can backup successfully to a windows-based network share. For another, when you uninstall KB5001347, your backup is working successfully, So can we presume that there is somthing imcompatible between your Synology and our KB5001347, since if your issue only occurs when backing up to Synology. So I may suggest you to seek for assistance from support engineers of Synology, to see if they have any ideas about this issue.

Thank you for your understanding!

Best regards
Joan

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Answer 2

@JiayaoZhu , I think you (mostly) summarized correctly. But I think further Microsoft engineers should take a look at this, because only this update runs into this issue. All previous versions were running with out any issue!

Answer 3

Hi,

Thank you for your patience!

After our discussion, my colleagues did many researches and I think I can offer you the following options, you can choose one from them based on your own condition:

1) Your issue needs further analysis of logs while it is beyond our Q&A scope, so if you want to further trace your backup logs to see why this issue happen, you may be suggested to directly seek for help from our engineer. In addition, if the issue has been proved as system flaw, the consulting fee would be refund. You can contact our engineers via:

https://support.microsoft.com/en-us/topic/global-customer-service-phone-numbers-c0389ade-5640-e588-8b0e-28de8afeb3f2

2) if just like our discussion, this issue is related to KB5001347 version, that is, the product design issue, then you can pend using this version and we can help you to feedback your issue to our product service group. However, since KB5001347 is the latest version, you may need to wait for a couple of days until our product release the next version, then you can try to install the next version.

3) You can also post your feedback on our KB5001347 version on the website:

https://windowsserver.uservoice.com/forums/295047-general-feedback

Thank you for your understanding and support! And If possible, can you "Accept Answer" for me? It seems to be a general issue and if you accept answer, then other people who have the same issue with yours can have a quick way to find their solutions.

Best regards
Joan

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Answer 4

Hi,

I have same problem with 2012 R2 server, after updated with KB5001382. Can not backup Hyper-V guests to Synology NAS.
After removed the update, work fine again.

Answer 5

Hi all,

I've created a new service request directly at Microsoft. I'll update here, if I get any news regarding this issue.

I told the service engineers the link to this thread.