We've had several issues where the customer has reported an error message such as:

Error; Unable to connect to vddk data source: connect_uri: nbd_connect_uri: handshake: server has no export named '': No such file or directory

or variations. This happens with both virt-v2v and when using libnbd directly (eg for warm conversions). Examples: CNV-44894 & customer case 03866462.

What is actually happening is that VDDK is producing an error message which nbdkit is logging. However the error is not propagated to the client (libnbd) and so libnbd / the client prints something very generic instead.

I have modified nbdkit (to store and send the error over NBD) and libnbd (to display the error) in these series:

https://lists.libguestfs.org/archives/list/guestfs@lists.libguestfs.org/thread/LPPZDH2KTFVBJVRKVGCLOMCDHAOFUCQY/

https://lists.libguestfs.org/archives/list/guestfs@lists.libguestfs.org/thread/XWE5OXI6UAECLNRUJWBIZ6GCP64KNRQC/

We should include these in RHEL 9.5 & 10.

The RHEL 9.5 backport might be quite tricky.

(Notifying eblake_redhat)