My experience with an in-place upgrade from 32 bit Win 7 pro sp1 to Win 10 pro.
Computer was 6 year old homebuilt with 4 year old ECS motherboard, 2 core ivy bridge pentium, 6 year old 1GB Radeon video card, 4GB ram and 4 internal HHDs. Other than the number of drives my system is about as vanilla and non cutting edge as you can get.
My plan was to clean up Win 7 installation, create disk image, clone Win 7 installation to new SSD and then do in place upgrade to Win 10 on the new SSD. Two problems turned this into a prolonged (8 hour and innumerable reboots) ordeal
Two significant problems I encountered (and others have encountered) with solutions that worked for me:
Problem 1. Samsung SSD software was used to create the existing Win 7 SSD a couple of years ago. It created 3 partitions on the OS SSD. The "data/system" partition was 100mb and was 99% full. That resulted in my inability to create a disk image using W7 tool or to do inplace upgrade with W10 tool since there was not room for a "shadow copy" during these processes. W10 did not announce this problem until about 45 minutes into the installation process. Internet forums suggest this not an uncommon problem
My solution was to use free tool "Mini Tool partition wizard" to expand the system partition on existing SSD which allowed creation of disk image and in place upgrade to W10. MS disk management could not expand the system partition since it was immediately adjacent to the OS partition.
Problem 2. I cloned the existing W7 drive to a larger SSD that I was going to use for the upgrade. Unfortunately for me one of the already installed HDDs in the computer had been a previous OS drive that I had not repartitioned or formatted but just left it in place. It had not previously been a problem but when I booted with the new W7 clone in place BIOS chose to boot from the old HDD and that boot process wiped out most of my W7 OS USB and proprietary motherboard drivers. In device manager I removed all 16 USB hubs/devices and restarted. Doing this several times did not restore the USB drivers. I was at a minimum back to ground zero.
Lessons learned: In a multiple HDD system with reused HHDs check that only one HDD contains a boot sector. Before reusing a HDD that previously was an OS boot drive be sure to repartition and reformat that drive. Also check BIOS boot sequence before booting after installing a new system drive.
Once I had a source disk with enough room in the system partition for a shadow copy and I had disconnected the older HDD containing a boot sector the upgrade went seamlessly. In retrospect I don't know if a clean install would have been less time consuming.
With what I know now I would:
1. Clean up my existing W7 installation by removing unused programs, updating W7 and running MS disk cleanup.
1. Create a clone or disk image of W7 disk with Macrium Reflect to have a backup.
3. Perform W10 in place upgrade. If that failed do a clean install of W10 using ISO or USB to get W10 activation.
4. Then either reinstall apps and data on the W10 clean install or restore W7 from the clone or image.
In the end my upgrade is functioning better than the Win 7 it replaced. The upgrade process for W10 scoured the internet and installation files to discover and install MB and USB drivers that just work. Also basic MS drivers for my 9 year old Canon printer and 7 year old epson photo scanner were installed with the upgrade so both devices worked. I installed Win 7 OEM software/drivers on top of the MS drivers for both of these devices to give more operational options and they are functioning without evidence of conflict.