As of today the Sparky automatic update tool seems to get stuck on updating.
It informs me that it want to 'upgrade' about 65 mb, which I accept. It 'updates', showing the embedded terminal window, but returns almost immediately to the update requester again, repeating the proces in an endless loop.
When I look at the changelog, the Sparky upgrade tool informs me that it wants to downgrade virtualbox.
How to deal with this situation ?
Finish the upgrade in a terminal emulator:
Thank you very much pavroo.
That solved it.