Eugene's observations

Having now installed Windows 10 several times a few gotchas and tips are ready to leave my fingertips.  Things normally (anecdotally 85% of the time) go well but I have personally encountered several failed installs so it is essential to take an image of your system partition before you begin.

• Virus and firewall protection is removed as part of an upgrade.  Make sure you know your account details or license key ready for a clean install (not repair) after Windows 10 upgrade completes. This must be your first job after the last automated reboot.
• Similarly Gadgets and widgets are likely to be messed with.  Simple to fix but preparation can ease the resolution.
• Video drivers - If you have a second (or third) monitor prepare for all bar one to be disabled.  Also, screen resolution may be changed.  The (Nvidia 353.62) driver update I tried to resolve this failed.  However, sit back and bide your time: Windows will automatically get a default driver soon that works just fine.
• One PC with an (AMD Radion) graphics card hung for 2 minutes at boot time.  Disabling the graphics driver removes the fault but causes lousy display.
• Wallpaper may be messed with.  Under 10 you cannot use a library so all images will have to be moved to a common root.
• Roboform password manager does not work in Edge - a second browser is therefore essential.
• Internet Explorer is well hidden on a clean install - you can get to it fom the setup menu of Edge.
• On at least one PC the taskbar got locked open and could only be rejeuvenated by restarting Explorer (from task manager) two or three times a day - there is currently no fix that I am aware of.
• If you already have a Win7 or Win8 PC you must upgrade BEFORE doing an clean install - the activation key will not work otherwise.  Subsequent clean installs are not a problem as keys are now held in MS servers.
• Some default programs are reset to their Modern equivalents, you may need to reassign after the upgrade.
• System Restore may be left off and need to be manually enabled.
• Although we lose control over updates we don't have to put up with loss of control over restarts after they are installed - Settings > Updates > Advanced > Notify to schedule restart.
• Access control on shared and network folders can be reset to defaults so needs to be checked.

These are just the issues I have personally encountered.  The forums are full of other problems that some people have bumped up against.  However, as time goes by it is expected that Microsoft will address these issues by way of updates.  It is probably wise to ensure you have a clean system before you start by following the process described in an earier blog.