Unable to update Windows 8.1

[vivekkalra]

My system is stuck forever while checking for Windows update (I need to upgrade to Win 10). Sometimes, after 1-2 hours, an error is hown (device unregistered). I have a genuine windows 8.1 Pro

[WAWood]

@vivekkalra 

While Windows update is generally the easiest way to upgrade to a new Windows version, it is also the one that fails the most often.

If Windows 10 v20.04 (or 20H1, depending on how you want to refer to it) is blocked on your PC, you can try to FORCE an update to the most current version of Windows 10 -- but that takes some work.

- Use Macrium Reflect to create a backup on a large USB stick or external drive (see below)

- Use this link to download and create Win10 install media: https://www.microsoft.com/en-us/software-download/windows10

- insert that into your PC (do NOT boot from it), find the folder containing the media, select the setup.exe file, right-click that and select Run as Administrator.  This will start an in-place Upgrade which could then take a couple of hours to complete.

If you are presented with a window asking for a product key, down near the bottom is a entry you can click to skip that. Do NOT enter a product key, as it will reuse your existing key and when you finish and get back online, Windows will automatically activate.

--------------- Doing Image Backup ---------------
I personally prefer to use third-party Backup solutions as they tend to be both more flexible and more reliable than any built-in solutions.

Macrium Reflect (MR) provides a FREE version that can be used to image and restore partitions or entire drives.

What I recommend is the following:
1) Download and install Macrium Reflect (MR) from here: http://www.macrium.com/reflectfree.aspx
2) Run MR and choose the option: "Create an image of the partition(s) required to backup and restore Windows" to write a full backup to an external drive or USB stick
3) Use the option to create a boot USB stick or CD

My experience is that MR, when using the High Compression option, typically can compress the saved image file to about 50% of the USED space in the OS partition. This means if you have an 80GB OS partition, and 40GB is used, MR only needs about 20GB to store the image file.

I use this all the time and it typically takes less than 15 minutes to do the image backup and about the same time or less to do a restore.

NOW, you have the means to restore a full working system from the external drive or USB stick in only a few minutes.