How big is your drive C:? I try and keep mine as small a possible by having programs and other stuff on drive D.

With a 128 Gb SSD for C, I can clone the drive daily as an essential backup. Today WD Green SSD sell as cheap as chips.

Actually last weekend I just increased the size to 240 Gb and reinstalled Windows 1703, along with a new motherboard, i310100 socket 1200 CPU and G.Skill 16 Gb RAM.

Total cost including delivery $A 537.95 - $US 391.54 GBP 296.26

That WD Green 240 Gb SSD only cost me $A 39.00, cheap for clone/image backup.

As you can see, I learned many decades back to keep drive C lean and mean.

Why would anyone try to update Windows 10 on 11/11? (Sorry- I've just been seeing a lot of Spinal Tap-related memes today...)

@engine ... what I do know is if you WAIT LONG ENOUGH the dang thing will eventually finish. As noted above, clear the boot drive of EVERYTHING THAT IS NOT WINDOWS and keep that as small as possible. The wait time will be much shorter.

Secondary, particularity if spinning rust, a chkdisk for ALL sectors will go a long way to making things run faster in the future (about every 6 months!).

I feel lucky, because, so far, I never had a problem with Windows updates. This one , went smooth too. I build my own computers and own standalone licenses of Windows , I don't know if this is related.

I had the same issue when my computer decided (against my wishes) to start the updates in the middle of the afternoon. Five hours later, I finally got my computer back. Although it makes me wonder sometimes whose computer it really is!

I don't understand the thinking of Microsoft about updates. My feeling is the updates have become more of challenge for users.
It's clear to me that some machines are fine, and others are a nightmare. My main machine is the latter.
Productivity is destroyed, and frustration and anxiety is very high.
If money and the environment were no object I'd replace the machine, but it's hardware is well specified with plenty of capacity.
It has to be a software clash of some sort, but is it possible to find it? The simple answer is no, it's not.

Microsoft's own "phone home" and unnecessarily intrusive software only adds to the problem.

Back to this latest update: After interrupting the update five times following the system crash, the machine is operating, and the update has not happened. If it's the security update, I need it, but I'm just not looking forward to starting the process again.

Just curious ... are there any exterior or multiple interior drives in use?

As early as Win7 when I knew an update was coming (never allowed the automatic, just notifications) I'd dismount or remove exterior drives and let the boot target do it's update in jig time.

YMMV.

However, removing any external drives never hurts and possibly PROTECTS data on those discs!

The short answer is no, there are no external drives.

I've spent many weeks investigating this and there are tons of solutions out there. Believe me, I've tried them all.,except reinstalling, which is a nightmare I don't want to have.

Interestingly, another Win 10 machine has crashed at the cleaning up stage.

Win 10 bootup is now typically 10 minutes before the machine becomes slightly usable. I start it 15 minutes before I'm likely to want it.
It's all windows processes happening at the same time, and I've done my best to stop some processes at the outset, such as indexing, phoning home, windows store, skype, etc. Windows wants those processes to start, but I don't.

Recently I had a problem with Avast antivirus messing up and slowing down my machine. I switched to Windows Defender, disabled a ton of software at startup and cleaned up the HD. Now it works fine. Maybe your problem is similar to mine?