Update:

There are no errors while backing up brand new VMs.
Error are occuring only on the same VMs, that were backing up already many times on our previous StorWare installations.

Backup of KVM fails with this error:

Info ExternalAPIException: Failed to execute remote command: [LC_ALL=C sudo qemu-img info --backing-chain /var/lib/libvirt/images/administrative/K8S_Alpn_MSTR-01.qcow2-vProtect-89b59650-dd1a-4167-8f65-fe3a573b7c74], return code: 1, error: [qemu-img: Could not open '/var/lib/libvirt/images/administrative/K8S_Alpn_MSTR-01.qcow2-vProtect-89b59650-dd1a-4167-8f65-fe3a573b7c74': Failed to get shared "write" lock Is another process using the image [/var/lib/libvirt/images/administrative/K8S_Alpn_MSTR-01.qcow2-vProtect-89b59650-dd1a-4167-8f65-fe3a573b7c74]? ]

Error Screenshot

It occurs either in scheduled multisession backups or in manual (on-demand) backup.

Storware Version 6.1.0-16
QEMU emulator version 6.2.0 (qemu-kvm-6.2.0-20.module+el8.7.0+16905+efca5d32.2)

P.S.
I don't think, that the problem is on the KVM-host,
'cause we had not such error on previous version of Storware (6.0.0-35),
the same KVM-host backups were working good,
but sometimes, we had the "Server has encountered the runtime error."
error on Storware 6.0.0-35 Version.

@djaw Thank you for the solution!
I'll try it!

I've just installed fresh vprotect server using all-in-one script.
Documentation link

Have exported SBR_ADMIN_PA*S and SBR_DB_PA*S variables in advance.

After the installation, i can't login neither with default pa*sword (vPr0tect),
nor with SBR_ADMIN_PA*S value.

Web UI error is: Provided credentials are incorrect (login or/and pa*sword)

CLI error is:
vprotect login -u admin
Enter admin pa*s:
ERROR: Provided credential is incorrect

Is it possible to reset admin pa*sword from CLI,
or some other ways?

But now i can't check the backup,
'cause i've already backups for 15 VMs,
and my trial license doesn't allow me to make any new backups. (10 VM limit).

Now i'm looking for the ways of deleting my previous backups......
Couldn't find yet......

Just set my expiration policy to 1 day,
if there are no other ways, i'll wait till tomorrow, untill my backups gonna expire by the policy.....

@Argus
no, i didn't choose the "backup destination for cloud" .

I've chosen "S3" in the 'Choose configuration' section at the "Edit node".
screenshot link

Then, at the
Edit Backup Destination - Amazon S3 / S3-compatible,
under "Choose Node Configurations"
i selected both: 'Default config' and 'S3'

screenshot link

@Argus
Hello!
Version is 6.0.0-24

I'll check now for the "node configuration" and reply soon

Hello!
i’m trying the storware, as a ESX-appliance.
I want to make backup of KVM VMs immediately to S3,
i’ve configured the S3 Object Storage, in the Backup Destination section.

But in the «Virtual Environments» policy, in the «PRIMARY BACKUP DESTINATION» — i can only choose the «File System».
I can’t choose an «Object Storage» — as a «PRIMARY BACKUP DESTINATION».

Is it possible, to send primary backup immediately to S3?