This is a long shot but maybe try to the nearest 10gb?
Attempting to increase a 20gb .vdi to 25gb, and running the following command from C:\Program Files\Oracle\VirtualBox> (on version 4.3.12)...
vboxmanage modifyhd "D:\VirtualBox VMs\VS14 CTP\VS14 CTP-disk1.vdi" --resize 25000
...returned
0%...
Progress state: VBOX_E_NOT_SUPPORTED
VBoxManage.exe: error: Resize hard disk operation for this format is not implemented yet!
but when I increased the new size to 30gb..
vboxmanage modifyhd "D:\VirtualBox VMs\VS14 CTP\VS14 CTP-disk1.vdi" --resize 30000
It worked...
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
I can't say anything else sensible to say at this point... :) At best the message is misleading.
i try this method : VBoxManage modifyhd YOUR_HARD_DISK.vdi --resize SIZE_IN_MB but it doesn't work – Ellouze Anis – 2013-01-31T14:18:19.237
2please provide the error message you get when you attempt to resize the disk – Steve – 2013-01-31T14:21:26.360
0%... Progress state: VBOX_E_NOT_SUPPORTED VBoxManage.exe: error: Resize hard disk operation for this format is not implemented yet! – Ellouze Anis – 2013-01-31T14:59:42.833
I guess VM guest OS is not running – jet – 2013-01-31T17:05:20.243