tl;dr 1 – C1900101-20017 means that the Windows 10 setup encountered an error on the first reboot and also means you’re screwed but read below for some hope.
tl;dr 2 – I reached out to Microsoft Support for help with this error and I give their first level support a B and second level support a big fat F. Either way they didn’t help.
You’re reading article this because you tried to upgrade your system to Windows 10 after a while it booted back to your old version of Windows and greeted you with the cryptic error code C1900101-20017:
Or maybe you were luckier and got this ever-so-descriptive 0xC1900101 – 0x20017 version of the error:
Explanation of the Problem
The error presented to us is “The installation failed in the SAFE_OS phase with an error during BOOT operation” and what it means in plain English is that the Windows 10 installer was in the middle of installing Windows 10, and it needed to reboot. But something wrong happened during the boot (for example, a driver crash leading to a Blue Screen of Death). Because the boot was unsuccessful, the Windows 10 installer terminated and returned your computer back to the version of Windows you had before.
The good news: At no point is your computer bricked. I’m thankful for Microsoft for ensuring that, even though I’m annoyed with their other decisions (see below) at the same time.
Why Does this Problem Happen?
Microsoft support would have you believe that this is because you have some faulty hardware. I strongly disagree. 99%+ of the time it’s a simple matter of a software bug. Typically, the driver that ships with Windows 10 has a bug in it, or the driver that you have installed currently on your system has some compatibility problem with Windows 10.
A hardware problem is a possibility (slim, but possible). For example, you may have a bad memory chip and Windows 10 just happens to put some critical piece of code at that faulty memory location triggering the problem.
Another reason to believe that this is usually a software – not a hardware – issue, is Microsoft Support’s insistence that I reformat/reinstall my computer. “In their experience” it almost always fixes the problem. Well guys, if reinstalling solves the problem, then it’s not hardware.
So How do I fix it?
The big problem is that Microsoft gives us no tools to figure out what exactly went wrong. Ideally there would be some sort of log file listing which driver was the last to initialize so we could guess what’s causing the problem, but there isn’t. At least, I couldn’t find such a thing at the typical setup log location ($windows.~bt\Sources\Panther).
That leaves you with the dubious pleasure of narrowing down the culprit using trial and error.
Step 1: Remove/Disable devices
** Before you start ** you should create a Restore Point so you can undo any damage you may do along the way. If you don’t know how to create a Restore Point then this guide isn’t for you.
The Microsoft support article which mentions this error computer recommends unplugging all your USB devices. I would take it a step further and unplug everything that you can, even internally. For example, if you have both an embedded and a dedicated video, remove the dedicated card and use the video card on your motherboard. At least until you can rule out your video card.
You should also open the device manager and go through the list. See a driver for a long-ago junked printer? Delete it. Clean up anything that seems out of place. (Usual disclaimer: Deleting drivers can cause your computer not to function/boot. See notice about about creating a restore point).
Step 2: Update Drivers
Make sure you’ve got the latest drivers for all your devices by downloading updated packages from the manufacturer websites. Don’t forget drivers for built-in peripherals on your motherboard. You should probably upgrade your BIOS to the latest.
Also Try: Install Windows 10 On Another HDD
Try reinstalling Win10 after doing Step 1 + Step 2. But if that doesn’t help, try this.
Remove the hard drives from your computer and plug in an old/new HDD you have laying around (you do have one laying around, don’t you?). Install Windows 10 on this hard drive using a Windows 10 DVD.
If the installation fails, hopefully you’ll get a better error before. This is because there is no “old windows” for the installer to boot back too. It will hopefully crash telling you what the culprit is.
In my case this installation succeeded which led me to eventually finding out the original culprit: The Intel RAID on my ASUS Sabertooth X58 simply doesn’t work at with Windows 10. I have found many complaints on the web, but no solution. My solution was to change the controller from RAID to AHCI mode and set up my RAID using Windows Storage Spaces.
Common Sources of The Problem
In researching this error, I found that many people we suffering from various instances of the problems listed below. You may fall under one of these categories:
- Broadcom WiFi drivers are known to cause problems during the upgrade. This may no longer be an issue since Windows 1511 was released, but if you have Broadcom WiFi in your device, try Googling for solutions specific to Broadcom.
- The Intel Rapid Storage Technology (RST) driver can cause problems. This thread talks about a possible solution for motherboards with the X58 chipset. As I mentioned previously, nothing worked for me other than changing the controller out of RAID mode.
If you had a different cause, please update me in the comments below and I’ll add to this list.
Regarding Microsoft Support
In my desperation I contacted Microsoft Support. I assumed there was some magic log file they could look at to solve the problem. I was greatly disappointed.
I started out using their chat service. The first agent took over my computer and tried to do a few basic things which didn’t work out. The next day I talked to another agent over the phone which tried a whole bunch of other things that also didn’t work. We continued on and off for 4 days and still nothing worked. Eventually I was asked, and was transferred to second level support.
I’d like to mention that I was impressed by the first levels support’s commitment. Although it was obvious they were running oof a script and didn’t really know hot to help me specifically, they were tenacious. They called me 3 times a day to see if my issue was resolved and to see if I wanted to keep diagnosing. They stayed with me on the phone for hours while the Windows 10 was installing over and over and were genuinely trying to provide dedicated service. All this for a product I’m not paying a cent for. Contrast that with Google (AdWords) support where I had to call in 8 times over two weeks to have a trivial matter resolved.
So why do I give them just a B? Mostly because it was obvious that most of their actions were a waste of time (e.g. clear out my temp folder and try to reinstall) as well as the fact that they did stupid things like leave my computer running without a firewall (not a problem for me but non-techies beware). The fact that I had to take control of my computer back from them a few times when it was obvious I could complete their tasks faster and better didn’t help either.
Second level support, on the other hand, gets a big fat F. The agent was arrogant and all he wanted to do was reformat my computer. I had to argue with him that I already knew that it would work (as I had installed Win10 on a different HDD) and I was interested in finding the hardware/driver that was causing the incompatibility instead of wiping my system. Eventually he agreed to look into it and put me on hold. After a long wait on hold, the call was disconnected, and he never called back. I gave up on them at that point.
Executive Summary: