Backup with error "Error: Failed to call RPC function 'FcWriteFileEx': An unexpected network error occurred"

[Dric_IT]

Hi the community,

We have a weird behavior with a backup (backup of vms with a hyper-v cluster 2 nodes to a nas)

The backup is running fine but every Friday ( not the day of synthetic full by the day, just a normal incremental backup day) we have this issue :
Unable to apply retention policy: failed to delete backup files Error: Failed to call RPC function 'FcWriteFileEx': An unexpected network error occurred. Failed to flush file buffers. File: [\\File:XX.XX.XX.XX\Backup\Backup VMs.vbm_24_tmp]. => always the same error with exactly the same file that doesn't exist !

The old files are normally purged although so it's not a big deal but still it's a concern.

If anyone encountered that already or have any idea!

Sincerely

[david.domask]

Hi Dric_IT,

Please open a Support Case and let Veeam Support review the behavior please. Be sure to include logs for the affected job for Support to review.

The issue at face value looks like generic SMB connectivity issue, but given that it's error-ing out on updating the VBM file (backup metadata), it's possible there are other factors that may lead to the error (e.g., firewall, AV on gateway)

It's best to start with a support case however as Support can review the behavior in the logs and give more specific answers as to the root cause.

Please share your case number once created. Thanks!

[Dric_IT]

Hi David,

Thanks for your reply.

Unfortunately we have no license (community edition).

If there is another way to transmit the logs, i'll be more than happy.

We thought about SMB problems but why this problem occurs only on Friday during a normal job. The synthetic job takes a long time and there is no problem. I checked on NAS if there is some maintenance tasks but nothing. Same for AV , nothing scheduled at this time.

Sincerely,

[david.domask]

You're welcome for the reply.

Community Edition is supported on a "best-effort" basis depending on Support availability; we won't be able to troubleshoot over the forums, so a Support case is still the way to go.

As for the issue, indeed the symptoms are a bit strange, but if there's a specific time frame when it's happening, that narrows it down a bit. Microsoft has this article which may assist, but I still advise a Support case.

Please share your case number once created, thanks!

[karsten123]

do you have your solution from Veeam support? maybe it is better to get rid of SMB.

[david.domask]

Hi karsten123,

The topic creator never shared a case so regrettably no update.

Unexpected Network Error here means pretty much as it tells, SMB encountered an unexpected network error, and typically this requires investigation of the OS / Network between the gateway and SMB server, and regrettably there are numerous reasons this can happen.

If you're experiencing it and cannot identify any immediate issue from a review of the gateway server / network, open a Support Case and let Support review the situation, they may be able to advise more accurate tests.

> maybe it is better to get rid of SMB.

In general, while SMB can work, often it's best to use any other options (nfs, iscsi, etc) if feasible