"Couldn't update to Windows 8.1 - 0xC1900101 - 0x40017"

I agree, I believe a clean install would work as well.  I'm glad I didn't have to do that and got to keep my files.  Saved a lot of time that would have been spent copying from my external.  A clean install was my last resort but I think the Disk Cleanup will have the same effect for the upgrade purposes and it wont be necessary.

May I point out to everyone, that you could try a manual installation. That means that you download the install disk ISO, for free from here: http://windows.microsoft.com/en-us/windows-8/upgrade-product-key-only and completley bypass the windows store.

Enter your product key, and then download the ISO, burn it to a DVD or use the Windows 7 USB download tool, so you can use a live USB to boot. Then BACK UP all of your home folder. That means going into your user name folder form the start, and then copying everything over to an external hard drive, or memory stick, or even a network location (people might be able to see your backups on a network location, so I would not recommend it, Also, if your PC can't boot, then the recovery CD is not going to give you any network connectivity if your PC cannot boot properly). This is the easiest way to backup, as you can see how quickly it is going, and how long it has left. Also go start, type recovery, (go settings if you are in windows 8) and then find the one in the control panel. Select create a system image in the left sidebar, and then select your location. Make sure you have enough free space, and if you do not, delete some files, or even put them on skydrive. When this has completed, I would also make sure that the windows 8 ISO lets you restore a system image, so if anything does go wrong, or you do not like windows 8.1, or if it does not work for you, you can restore your backup using the live USB. Also, I would then do a clean installation, delete your Windows partition, create a new one, and then install windows 8 to that. You will have to re install your programs, and copy your user folder back to the one on 8.1, but it means that the upgrade will work...

This has not been tested by me, but it probably will work.

Hope this helps

George

I have successfully upgraded to 8.1 my son's laptop (Medion razer with i7-4700MQ,GYX765M and Samsung ssd + Sata disk).

But on my DELL inspiron R15,64bits which came with win8 pro 64bits it always fails. This laptop is encrypted with McAfee EEPC7. I have did all suggested solutions it always fails. I do not get a bsod but at the end of installation when I am expecting that laptop is starting with win 8.1, it says We are sorry we couldn't install 8.1.........etc.

I don't like that advice to disable apps in task-manager.

First, it only disables stuff for the currents session, after a reboot, the incompatible programs will start up again.

Second, it doesn't tell you which applications to stop.

Third, it does not mention drivers that might not be compatible.

Do a clean boot instead. Setting up a clean boot using MSconfig will disable everything not needed by the update even after several boots-up, even the ones the update does when updating to 8.1

After, you complete the update and 8.1 is working, you can go into msconfig again and re-enable the non MS programs to start up normally.

Here is the basic steps for doing a clean boot. At the end of this post I included a link for all the details on setting up a clean boot and restoring the regular boot later, plus troubleshooting tips should you have a a problem with one application or driver.

Follow the following steps to perform a clean boot on Windows 8

Swipe in from the right edge of the screen, and then tap Search. Or, if you are using a mouse, point to the lower-right corner of the screen, and then click Search on the charms bar.

Type msconfig in the search box, and then tap or click msconfig.

On the Services tab of the System Configuration dialog box, tap or click to select the Hide all Microsoft services check box, and then tap or click Disable all.

On the Startup tab of the System Configuration dialog box, tap or click Open Task Manager.

On the Startup tab in Task Manager, for each startup item, select the item and then click Disable.

Close Task Manager.

On the Startup tab of the System Configuration dialog box, tap or click OK, and then restart the computer.

On the General tab, click the Selective startup option, and then click to clear the Load startup items check box. (The Use Original Boot.ini check box is unavailable.)

On the Services tab, click to select the Hide all Microsoft services check box, and then click Disable all.

*** When you hide all MS services, the remaining services are third party programs and extended driver features that are likely to mess up the update. you will see things like ExpressCache,Google Update, Nvidia, Logitech, etc. DISABLE ALL OF THEM *** (but don't disable any MS services)

Note This step lets Microsoft services continue to run. These services include Networking, Plug and Play, Event Logging, Error Reporting, and other services. If you disable these services, you may permanently delete all restore points. Do not do this if you want to use the System Restore utility together with existing restore points.

Click OK, and then click Restart.

Now go to the Store and run the 8.1 update.

By my estimation, this should work for about 80% of the people who posted to this topic.

If you have moved the \users folder to another drive by any method not approved by Microsoft, done any registry hacks or used any third party utilities that mess with the physical hard drives, the upgrade may still fail. You may have to remove all partitions from the physical boot disk and remove any Dynamic features from the drive. You should also unplug all USB devices except the keyboard and mouse, then turn off any Bluetooth devices.

A complete description for setting up a clean boot, along with restoring it to a normal boot and troubleshooting the apps that may not work on 8.1, along with screen shots can be found on the Microsoft site here: http://support.microsoft.com/kb/929135/en-us

For Error 0xC1900101 - 0x40017

I finally got Windows 8.1 to install by using these steps first, along with some others given by Rakesh Jain.  As I said I first performed the steps listed above.  Everything, step by step.  I then tried to install Windows 8.1 with no success.  Then I saw another post which sparked my interest and I thought it may be the problem, since I upgraded from Windows 7 to Windows 8 without doing a clean install, Rakesh's method made perfect sense to me.  So I then,

Hi

     Do a repair of your windows 8 (Inplace Upgrade). Once the upgrade is completed remove all the 3rd party antivirus programs. Install all the updates from store and windows update. Run a disk cleanup and cleanup all the files including the system files from disk clean up and then try to install windows 8.1 this works.

Thanks

Rakesh Jain

Which is Rakesh's post.  Which can be found at this page.

http://answers.microsoft.com/en-us/windows/forum/windows8_1-windows_install/couldnt-update-to-windows-81-0xc1900101-0x40017/e1ee316f-f912-43ef-92dc-ee31a5fe62d9?page=33&tm=1384283684963

I tried to repair Windows 8 but it said nothing needed to be repaired.  I then uninstalled Norton, my anti virus software.  I installed all updates from Windows update and Windows store.  This next step is the step which I believe made the difference.  I then ran a disk cleanup and cleaned up all the files including the system files.  Went to the store and upgraded to Windows 8.1 with no problems.  So it was a combination of these two posts which lead me to be able to finally get Windows 8.1 installed.  It was becoming very frustrating after trying to install 10 or more times.

I've had this problem 6 times since the original public release of 8.1.  I've disconnected everything except my keyboard/trackpad & monitor and tried to run the 8.1. update; same old problem.  In frustration, I contacted MS Support.  Over 3 days and 10 hours of elapsed time later, the problem still occurred even when I let MS Support take control of my machine (yikes).  Their final answer?  "Pay us $99 for "Premium Support" and we'll fix it for you."  Really?  Really?!  I told them no thanks, I'll stick with 8.0 for now.  Geez, I was brave enough to buy and install 8.0 when it first came out (against my better judgment) and now MS wants to charge me to add their faulty "upgrade"?

I think NOT, Microsoft.  Build better products, support your products freely (especially for early adopters), and stop treating your loyal customers like dirt.