How to Fix: Windows 10 Safe OS Phase Error

Dennis Faas's picture

Infopackets Reader Shelby C. writes:

" Dear Dennis,

I am in a huge hurry to upgrade my machine to Windows 10 because there won't be any more security updates for Windows 7 in January 2020, when Windows 7 reaches its end of life. I have tried to upgrade using the Upgrade Assistant and Windows 10 media, but I keep getting 'SAFE_OS phase error during Replicate_OC operation' error, whatever that means. Windows 10 simply won't install on my machine! I have looked at articles all over the Internet including one from the Windows Club and none of them work. I really need your help! Can you please tell me how to fix this 'Safe OS Phase Error During Replicate OC Operation' error? "

My response:

I asked Shelby if she would like me to connect to her PC using my remote desktop support service in order to have a closer look, and she agreed.

Below I will discuss my findings.

Windows 7:  No More Security Updates January 2020

As Shelby mentioned above: come January 2020, Windows 7 users are no longer eligible to receive security updates from Microsoft.

This is a huge problem because it effectively means your Windows 7 system won't be protected against security exploits. This means hackers can infiltrate your system regardless of whether you are running antivirus, antimalware, or a firewall once a security exploit is discovered - which always happens. Trust me, it's just a matter of time!

They are able to do this because the operating system isn't patched, which means that they can obtain elevated access (typically through a memory buffer overflow through the exploit), which then allows them full access to the system. Here's an example of such an exploit. Here's another one that deals with Internet Explorer.

The only way to avoid this from happening is to use an operating system that is support, such as Windows 8 or 10.

I repeat: antivirus and antimalware WILL NOT PROTECT YOU from an operating system exploit, no matter how much "protection" you may have on your system. Read this article which explains what I just said in more detail. Note: If you need help upgrading to Windows 10, you can contact Dennis here.

Now that this it out of the way, let's get one with the rest of the problem.

How to Fix: Windows 10 Safe OS Phase Error During Replicate OC Operation

After much research into the issue and after attempting many different so-called "fixes" to resolve the "SAFE_OS phase error during Replicate_OC operation" error, the only thing that worked for me was to backup Shelby's system and do a reinstall of Windows 7.

Option #1: Reinstall Windows from the Desktop (Clean)

I was able to do this by having Shelby insert her Windows 7 DVD, then I ran the setup.exe program directly from the desktop.

Using this method, she did not have to boot off of her Windows 7 media in order to start the Windows 7 reinstall. This can be especially problematic if the BIOS boot sequence isn't set to boot from DVD or USB.

After this was completed, she inserted her Windows 10 media and we upgraded to Windows 10 without a hitch. The only caveat with reinstalling Windows clean is that she had to reinstall all her programs and re-customize the operating system after Windows 10 was installed.

There is another option that will allow you to keep programs, described next, though it's a lot more risky and has a 50% success rate.

Option #2: Reinstall Windows 7 or 8: Keep Your Programs

Another option is to do an in-place upgrade of Windows 7 or 8 using Windows 7 or 8 media. This will keep your programs and user data in place and 'reset' your existing Windows 7 or 8 installation, though there are a few caveats with this method.

First, you will need to make a backup in case the in-place upgrade fails.

Secondly, since the in-place upgrade effectively overwrites your already-patched operating system and reverts to back to 'factory' versions, some of your installed programs may stop working properly. In this past I have experienced these type of problems with .NET framework and MS Office (especially) after an in-place upgrade.

Third, the in-place upgrade may fail completely and leave you with a completely trashed system which may or may not boot properly. As such, be advised that this method has a 50% success rate. It will either work, or it will fail - and sometimes it may fail miserably. As such this is a risky method; if you don't know what you're doing, please contact me and I can manage it for you.

Option #3: Boot Media / Clean Install / Wipe Out Partitions

Yet another option - similar to the first - is to wipe the drive completely and reinstall Windows 7 or 8, then jump to Windows 10.

In almost every instance where Windows 10 fails to install, this method usually always works because you are literally starting from scratch, which also fixes all the weird Windows 10 installation errors during an upgrade. Of course, you will need to make a proper backup first (disk image is recommended) before proceeding with this option.

A few caveats here: this method is much more involved than the first and requires considerably more technical know-how. The reasoning here is that you be booting off Windows 7 or 8 media (assuming you own it), which also requires modifying your boot sequence in the BIOS so that the media boots before the hard drive (so that you can initiate the installation). Whew!

Assuming you made it that far, during the Windows 7 or 8 reinstall you will need to wipe out all partitions on the C drive until there is nothing but unallocated space, then click "Next" to the OS onto that unallocated space.

Once you reach the desktop, don't bother with updating Windows 7 or 8; instead, proceed to install Windows 10 directly from Windows 10 media.


This is the short-but-sweet explanation of ways you can overcome the Windows 10 Safe OS Phase Error During Replicate OC Operation error. This of course assumes you don't encounter any other obstacles along the way, which may happen depending on your system configuration.

If you are not tech-savvy and if you need help with upgrading your machine to Windows 10, I am available for 1-on-1 support to help you get past this issue - described next.

Additional 1-on-1 Support: From Dennis

If all of this is over your head, and you need help upgrading to Windows 10, I can manage the installation for you. This includes backups pre- and post installation, plus manual optimization (by me) of the system so that it's running as fast as possible. To get in touch, simply contact me using the contact form on this website and I'll get back to you as soon as possible.

Got a Computer Question or Problem? Ask Dennis!

I need more questions. If you have a computer question - or even a computer problem that needs fixing - please email me with your question so that I can write more articles like this one. I can't promise I'll respond to all the messages I receive (depending on the volume), but I'll do my best.

About the author: Dennis Faas is the owner and operator of With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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DLStoehner's picture

OK... So I have performed an in-place upgrade from Windows 7 to Windows 10 that failed. I tried more than once - failed each time. Several different errors codes. Now my question is this: I perform a complete wipe of the system - install Windows 10 from the ground up with an ISO that I burned from a Media Creation download. It now needs to be activated. Do I insert the Windows 7 product code that I have from my old Windows 7 install? What if it doesn't activate? I try the slmgr command and it still does not activate. What do I do next? Do I now need to purchase a Windows 10 license? It is supposed to be a free upgrade.

Dennis Faas's picture

To maintain your free license upgrade you need to install Win7 either destructively or non-destructively as described in the article and then perform the upgrade to 10. You *** CANNOT *** boot from Win10 media and install clean or you won't get your free license.