[Solved] Access denied on Virtualbox.xml

[mp1]

I have created a new VDI by copying another one and then changing its uuid. When using the Virtual Media Manager to Add the new VDI to the portfolio of VDIs, I get the following error message:
Failed to open the hard disk Z:.....vdi (i.e. the new VDI I try to add)
Could not save the settings in C:....\.VirtualBox\Virtualbox.xml (VERR_ACCESS_DENIED)

Details
Result Code:
VBOX_E_FILE_ERROR (0x80BB0004)
Component:
VirtualBox
Interface:
IVirtualBox {3f4ab53a-199b-4526-a91a-93ff62e456b8}

I may view the VirtualBox.xml file when double-clicking on it. I wonder if there is a limit to the number of virtual hard disks and/or virtual machines that can be handled.

[vbox4me2]

VBox can't be running when doing that, make sure its closed or reboot the Host.

[mp1]

Thank you. Rebooting the host did the trick. Considered as solved.