Webinterface VHD(uncompressed) image mount failure

Debian Buster
kernel 4.19.0-9-amd64
urbackup 2.4.12

This is what I get when I run
urbackupsrv run -v debug
and select a VHD image from the backups (full image, not incremental)

any Idea what I’m missing?

besides that everything seems to be running correctly

Thank you so much,
ttyllc


BTRFS TEST OK
2020-07-06 07:41:47: Backup destination does handle subvolumes and snapshots. Snapshots enabled for image and file backups.
2020-07-06 07:41:47: Testing if backup destination can handle filesystem transactions…
2020-07-06 07:41:47: Testing for hardlinks in backup destination…
2020-07-06 07:41:47: Could create hardlink at backup destination. Hardlinks enabled.
2020-07-06 07:41:47: Testing for reflinks in backup destination…
2020-07-06 07:41:47: Could create reflink at backup destination. Reflinks enabled.
2020-07-06 07:41:47: Binding to interface eno3 (ipv4) for broadcasting…
2020-07-06 07:41:47: Broadcasting on ipv4 interface eno3 addr x.x.x.x
2020-07-06 07:41:47: Downloading version file…
2020-07-06 07:41:48: Downloading version file…
2020-07-06 07:41:48: Downloading server version info…
2020-07-06 07:41:48: Downloading dataplan database…
2020-07-06 07:42:52: ERROR: Thread exit with unhandled std::exception basic_string::_M_create
terminate called after throwing an instance of ‘std::length_error’
what(): basic_string::_M_create
Aborted

any help ? please?