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Note that the answer accepted for this problem appears to only be applicable to systems using some form of full disk encryption.

I just tried to install windows 8.1 on my laptop, but it fails to install with the message:

Sorry we couldn't complete the update to Windows 8.1.
We restored your previous version of Windows to this PC
0xC1900101 - 0x20017

The update installed just fine on my desktop. The difference between the two machines is that the desktop has media center install, and isn't using TrueCrypt.

On the first reboot for the update, the laptop goes to the PC restore screen. Thus far I have just been selecting "Continue to windows 8."

Full WindowsUpdate.log http://pastebin.com/hGmAW4Q1

Update: Turns out it was TrueCrypt! I decrypted the drive, installed Windows 8.1, and then re-encrypted the drive and it worked just fine.

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Could you post a screenshot of your system properties removing any personal information before you do so? Are you using full disk encryption by chance on the laptop? –  Ramhound Oct 17 '13 at 16:57
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I googled something which sugested to browse to the C:\Windows directory and look for a file named WindowsUpdate.log. Search for the code "0xC1900101" to see if there is any indication of what the updater was doing at the time the code was logged. –  horatio Oct 17 '13 at 17:00
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I am using full disk encryption, provided by TrueCrypt. According to Microsoft, TrueCrypt 7.1 is compatible with Windows 8.1. –  cmorse Oct 17 '13 at 17:01
    
you should decrypt the HDD before doing the update. –  magicandre1981 Oct 17 '13 at 17:34
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@cmorse I decrypted my truecrypt encrypted boot-partition, updated to 8.1, and now I'm encrypting my boot partition again (I have multiple partitions, but only touched the boot/windows one) –  flindeberg Oct 18 '13 at 13:36

6 Answers 6

up vote 7 down vote accepted

You should decrypt the HDD before doing the update. TrueCrypt is a 3rd party encryption and during setup Windows doesn't know how to handle it.

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This was actually the case, it worked fine when decrypted. And now I'm encrypting again :) –  flindeberg Oct 18 '13 at 13:37
    
ok, nice to hear that it worked. –  magicandre1981 Oct 18 '13 at 17:11
    
Alright, sounds like I don't have much of a choice...honestly, it seems odd. I've installed windows service packs many times with full disk encryption enabled with no problems. I'll try decrypting and then doing the update tonight. –  cmorse Oct 18 '13 at 19:25
    
I hope you read my answer below before you (potentially) waste your time. Decryption may be necessary, but it would be a shame if the installation still fails, and it just might. –  Michael Grant Oct 18 '13 at 20:27

I'm concerned that the answers provided here are going to lull the original poster, and others who may read this post, into a false sense of confidence that decryption is a slam dunk solution.

It's not. My installation failed with exactly the same error code; however, I do not use encryption. Larry Magid had the same error, and he does not mention encryption. Google searches turn up a number of instances of this exact error, many of which do not involve encryption.

In my view, the evidence is clear that the upgrade package is significantly flawed, and we need Microsoft to issue an updated version that corrects this.

The best answer, in my view, to this problem is: wait a week or two. And in the meanwhile, please consider submitting a bug report to encourage them to hurry.

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I wish that Larry Magid had been more specific about what exactly Microsoft support did to fix it! But it does seem that decrypting solves the problem for a lot of people, so, it is worth a shot if you do have full disk encryption enabled. –  cmorse Oct 19 '13 at 18:01
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Agreed. I am glad that encryption was the sole issue for you. But it looks like the error code we are seeing is a "catch all" for every issue the MS did not specifically anticipate. –  Michael Grant Oct 19 '13 at 22:50
    
That would explain the number of views that this question has been getting. –  cmorse Oct 20 '13 at 18:00
    
I disabled/removed a few devices I don't use anymore before the upgrade to Windows 8.1. Especially Western Digital's WD SES Device driver, which seemed to be causing the issues for me. The upgrade ran smoothly the second time. –  Vinayak Jun 4 at 6:53

I'm using WinMagic SecureDoc (6.1 x64) and my update failed as well with the same error. This may be indeed something connected to encryption.

As Win 8.1 is supposed to have a built-in auto-encryption there may be some conflict...

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Yepp, it is the encryption indeed. Not TrueCrypt only. BitLocker and I think that any kind of an encryption sw will cause this. It does not really matter whether the sw is or is not compatible with Windows 8.1. The 8.1 update runs fine after the HD is decrypted.

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There is no choice, you must decrypt the drive before the upgrade.

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Yes Just Decrypt the Disk or Volume! I used PGP and after decryption updated fine!

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Did you get the 0xc1900101-0x20017 error when the disk was encrypted? Was it the boot-partition? –  flindeberg Oct 18 '13 at 11:11

protected by random Oct 19 '13 at 2:06

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