I upgraded from SuSE 13.2 to Leap 42.3 two days ago.  Prior to the upgrade, my
Windows  virtual machine worked, but now it does not.  The message that shows
is the same as when i issue the the command: (run as root)
> qemu-img convert Windows10-2017-07-31.qcow2 Windows10.qcow2
qemu-img: Could not open 'Windows10-2017-07-31.qcow2': Could not open backing
file: Could not get image size: File too large 

> ll Windows10-2017-07-31.qcow2
-rw-r--r-- 1 root root 62G Jul 29 17:39 Windows10-2017-07-31.qcow2

It is not clear that the size is actually the problem:
> qemu-img convert Windows10-2015-03-21.qcow2 Windows10.qcow2
qemu-img: Could not open 'Windows10-2015-03-21.qcow2': Could not open backing
file: Could not get image size: File too large
> ll Windows10-2015-03-21.qcow2
-rw-r--r-- 1 root root 24G Mar 21  2016 Windows10-2015-03-21.qcow2

Since even a 24 GB file is too large, it is not clear how small a file is
required; i can find no documentation on the max file size.  But it is
important to note that this worked well prior to the upgrade from 13.2 to 42.3.

I am currently unable to use my virtual Windows machine as a result and i need
this to perform some work that requires Windows.