Vmware Powercli import-vapp command fails with an "internal server error"

Hi.

I exported my 3 templates from my Vcenter server to my local disk using the OVA format (one single file).

Using the Vcenter client, I can re-import my 3 templates.

However , when i use the powercli command "import-vapp" to re-import my "windows" template again, it fails with the following error:

Import-vApp : 19-7-2016 14:15:20    Import-VApp        Error while uploading virtual disks. (InternalServerError: Internal Server Error)
+ Import-vApp -Source  "<template path>"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [Import-VApp], ViError
    + FullyQualifiedErrorId : ViCore_VappServiceImpl_ImportVApp_DiskUploadError,VMware.VimAutomation.ViCore.Cmdlets.Commands.ImportVApp

The windows template uses 2 disks.
- One system disk of 40Gb. (C:\)
- One data disk of 10 GB. (D:\)

As a test I deleted the "system" (C:\) disk from the template, exported again and re-tried the import.
I was able to import successfully re-import the "windows" template after deleting the "system" (C:\) disk

The 2 other "Centos" templates are imported successfully using the "import-vapp" powercli command.

In the end, i'm trying to sync all my Vmware templates accross several Vcenter environments.

Hope someone can help me.
Thanks.