I am using Win 10-1607 and Macrium Reflect ver 6.3.
When I try to clone my Hard drive , I get and error "The following drive is in use and the restore can not continue ..."
This error first occured a week ago.  Before the clone was working and had been for months.

You'll most likely get that msg if you're trying to use any LOCKED drive currently connected to the System you're cloning from.  Without any additional details on your setup, it's hard to offer any guidance as far as this problem is concerned.  My guess... the "clone" is configured on your System and something is using it besides the cloning procedure itself.

I do not know what a locked drive is. Windows did install an update just before the cloning problem occured.

A "locked" drive is one that is currently being used by another task on your System.  For you to clone/restore any drive on your System, under LIVE WIndows, it must be unlocked.  That's why you cannot restore an image to your Windows System partition under LIVE Windows... it is locked (being used by lots of other processes).  To restore a Windows partition, you must use Reflect's Recovery Media to do that type of restore.

If any task on your System is trying to access the drive you want to use as your clone, it will be locked at that time.  When that task is finished, it should be unlocked.  Most DATA drives (mounted on a System but not being used at the moment) come up unlocked after a reBOOT and remain that way until some task tries to use it.

Maybe a System RESTART would help...

For Froggie
What additional info do you need. The computer does act like it is receiving a command to restore the C:/ drive, not clone it.

For froggie
I have restarted and shut down several times.

I still get the same failure using SAFE MODE.     "The following drive is in use ..."