When you try to update Windows (either upgrading from Windows 7 or 8 to Windows 10, or from Windows 10 to Windows 11) and the message appears “The installation failed in the SAFE_OS phase during the boot operation”The feeling is one of total gridlock: the assistant seems to be working fine, the PC restarts… and suddenly everything goes back to that cryptic error.
This failure in the SAFE_OS phase is not a simple one-off error: it is usually related to Problematic drivers, external devices, BIOS/UEFI settings, insufficient disk space, or even corrupted Windows Update filesThe good news is that it can almost always be fixed at home by following a series of ordered steps, without needing to format initially or lose your files and programs.
What does the error in the SAFE_OS phase and related messages mean?
During the update, Windows goes through several phases. The first phase SAFE_OS This is an early and critical stage, where a secure environment is prepared for the new system version. When something goes wrong here, you'll see messages like:
- The installation failed in the SAFE_OS phase with an error during BOOT operation (0xC1900101 0x20017, very typical).
- The installation failed in the SAFE_OS phase with an error during migrate_data operations.
- The installation failed in the SAFE_OS phase with an error during apply_image operations.
- The installation failed in the SAFE_OS phase with an error during replicate_os operations.
- The installation failed in the SAFE_OS phase with an error during install_updates o prepare_first_boot operations.
All these messages point to the same thing: The preparation of the secure environment to apply the update has crashedThe most common causes, according to user experience and technical forums, are:
- External devices connected devices (USB drives, printers, USB network cards, etc.).
- Corrupted, outdated, or incompatible drivers (especially graphics, storage, networking, card readers).
- Corrupted registry entries or system settings related to Windows Update or critical services.
- BIOS/UEFI incorrectly configured (Secure Boot, UEFI/Legacy mode, TPM, number of active cores, etc.).
- Lack of disk space or hard drive with damaged sectors.
- BitLocker or other encryption interfering during the update.
In many cases, when this error occurs, the computer automatically reverts to the previous version of Windows. From there, you will need to re-release the update but by applying the solutions that we will see below.
Common causes of the SAFE_OS phase error when installing or updating Windows
To be able to tackle the problem properly, it's extremely helpful to understand What is usually behind the SAFE_OS phase error?The list is not short, but the same culprits appear time and time again:
- Troubled peripheriesExternal hard drives, USB drives, hubs, printers, WiFi cards, etc. Sometimes just leaving a keyboard and mouse is enough.
- Device drivers Damaged components include: GPUs, SATA/NVMe storage controllers, network adapters, card readers such as Realtek RTS…
- Windows Update services misconfigured: BITS (Background Intelligent Transfer Service), Cryptographic Service and Windows Update Service in disabled or manual mode.
- Errors in the registry or remnants of previous installations that leave the system "dirty".
- BIOS/UEFI problems: Secure Boot incorrectly configured, UEFI/Legacy mode that does not match the partition style (MBR/GPT), TPM 2.0 disabled when we talk about Windows 11, number of active cores, etc.
- Hardware in poor condition or with limited resources: Faulty or insufficient RAM, damaged or poorly spaced mechanical hard drive.
- Corrupted ISO image or USB installation: faulty download, badly burned USB or ISO of unreliable third-party programs.
- Third-party antivirus and firewalls that interfere with system processes while attempting to update.
With this in mind, the idea is to tackle these factors one by one until The installation passed the SAFE_OS phase without complaint..
Essential first steps before tackling anything serious
Before getting into the nitty-gritty with BIOS, partitions, and so on, it's vital to do a series of basic checks that prevent many problems And, incidentally, they reduce the risk of losing data if something goes wrong.
1. Backup and sufficient free space
Don't assume that nothing will ever happen: a failed update at the worst possible time can leave the system unstableTherefore, it is advisable to:
- Make a copy of your important files (documents, photos, projects) on an external drive or in the cloud.
- Check that the system drive (usually C:) has at least 20-30 GB freeWith Windows 11, more is better.
- If you're running low on space, free up space by deleting temporary files. transferring programs and files to another drive And if you've already tried to update before, Cleaning C:\Windows\SoftwareDistribution\Download (folder where old Windows Update downloads accumulate).
2. Disconnect external peripherals
One of the simplest and most effective methods recommended by both Microsoft and users is disconnect all non-essential external devices:
- USB flash drives, external hard drives, USB hubs, printers and scannerswebcams, USB WiFi cards, etc.
- If you can, use a PS/2 keyboard and mouse instead of USB during installation.
- On desktop computers, it might even be worthwhile temporarily remove PCIe cards extra (sound, network, capture cards) if you suspect them.
The idea is that, when you start the installer or the update wizard, the system will be with the minimum possible hardware connectedthus reducing the chances of collisions with unusual drivers.
3. Disable antivirus and disk encryption
Security programs are necessary, but During a major upgrade, they can be a real pain.. It is advisable:
- temporarily disable your third-party antivirus, additional firewall, and any "security" software that monitors the system.
- If you use BitLocker or disk encryption Similarly, disable it from the Control Panel: System and Security > BitLocker Drive Encryption > Suspend protection.
Once the installation completes without errors in the SAFE_OS phase, you will be able to return to enable protection no problem.
Set key Windows Update services to automatic
Many cases of the "Installation failed in the SAFE_OS phase" error are resolved simply by correcting the configuration of some basic services that Windows needs to download and apply the update:
- Smart background transfer service (BITS).
- Cryptographic service.
- Windows Update Service.
To review and set these services to automatic mode, the standard procedure is
- Pulsar Win + R, to write services.msc and confirm.
- Search the list “Intelligent Background Transfer Service (BITS)”, "Cryptographic service"And"Windows Update".
- Open the properties of each one, put Start type set to “Automatic” and apply changes.
- Restart your computer and try the update again.
This simple adjustment has allowed many users Going from a SAFE_OS error to a completed update without touching anything else.
Drivers and hardware: the most problematic part of SAFE_OS
The other major source of headaches are the device driversThe code 0xC1900101, which often accompanies SAFE_OS, almost always indicates driver problems. This is where we need to be a bit more precise.
Update or review critical drivers
The most delicate For a Windows update, they are:
- Graphic card (NVIDIA, AMD, Intel).
- Storage controller (SATA, NVMe, RAID).
- Network adapters (LAN and WiFi).
- Card readers (for example, Realtek RTS, which is explicitly mentioned in some cases).
You can update the drivers from the Device administrator (right-click on Start > Device Manager), but it is usually more effective Download the latest version from the manufacturer's website of the equipment or component.
Real-world example: Realtek card reader causing SAFE_OS
In one specific case of a user trying to upgrade to a new build (24H2), the error log pointed to the driver package rtsbastor.inf The Realtek card reader was identified as the source of the problem. The recommendation was:
- Download the tool Driver Store Explorer (from GitHub).
- Use it to export all controllers to a folder as a backup.
- Locate and uninstall rtsbastor.inf from the tool itself.
- Relaunch the Windows update.
If in your case the installation record It points to a specific driver as the culprit; the idea is similar: Remove the problematic driver temporarily, update it, and then reinstall it. with a compatible version.
Temporarily disable the dedicated graphics card
On some devices, the message SAFE_OS appears during operation apply_image This is because the Dedicated GPU doesn't play well with the installerTo rule it out, there are two ways:
- In Device Manager, uninstall the GPU driver dedicated and force the system to pull the integrated one.
- Enter in the BIOS / UEFI and disable the dedicated graphics card (or prioritize the integrated one) following the manufacturer's manual.
On a desktop PC, you can also connect the monitor to the integrated video output The drivers should be from the motherboard, not the dedicated graphics card, during the installation. Once the system is updated, reinstall the official drivers and restore the configuration.
Adjust or check the RAM memory
RAM is rarely the only culpritBut if you've already tried everything else and are still getting the SAFE_OS error, it's best to:
- It tienes multiple RAM modules, leave only one installed and attempt the update.
- Check that the memory is not overclocked with aggressive XMP profiles.
- For older computers with 4 GB or less, seriously consider upgrade RAMespecially if you're aiming for Windows 10 or 11.
Some users have been able to complete the installation simply by removing additional modules or replacing the RAM which caused problems.
BIOS, Secure Boot, UEFI and Windows 10 and 11 requirements
Another major factor influencing SAFE_OS errors and messages like “This computer cannot run Windows” is the BIOS/UEFI configuration and the compatibility of the computer with the version of Windows you want to install.
Windows 11 compatibility: TPM, Secure Boot, and GPT
Windows 11 is considerably more demanding Windows 10. To install it officially, your PC must meet, among other things, the following requirements:
- Processor relatively modern (Intel 7th generation or higher, AMD equivalent or higher, according to Microsoft lists).
- Minimum 4 GB of RAM.
- At least 64 GB storage.
- System disk with partition in GPT and boot into mode UEFI.
- Secure Boot enabled.
- TPM 2.0 enabled in BIOS/UEFI.
If any of these points are not met, it is quite likely that the Windows 11 installation will fail, return SAFE_OS errors, or display messages like “This computer cannot run Windows 11There are third-party tools that help check compatibility and convert MBR disks to GPT, but the important thing is to understand that for To avoid installation errors, ideally UEFI, Secure Boot, and GPT should be aligned. with what Windows 11 expects.
Errors with GPT/MBR partition style
If the installer tells you something like “Windows cannot be installed on this disk, the selected disk has a GPT partition style"or the opposite message (that it needs GPT and the disk is in MBR), is a clear lack of coordination between:
- Start mode BIOS/UEFI: Pure UEFI, Legacy BIOS or mixed mode.
- Partition table of the disk: GPT or MBR.
The solution lies in deciding which standard you are going to use:
- For modern computers and Windows 11, the recommended option is UEFI + GPT + Secure Boot activated.
- On older computers with only a classic BIOS, there is no other option but to Legacy + MBR.
If you need to repair the partition table because the installation fails with corrupted file messages, you can use the following combination during the wizard itself. Shift + F10 To open the console and run:
- diskpart
- list disk to watch records.
- salt disk 0 (or the number that comes up).
- clean to clean the disk (this erases all partitions, be careful).
After this, the assistant will be able to create the necessary partitions from scratchreducing the probability of SAFE_OS errors due to disk conflicts and facilitating repair the Windows Boot Manager.
Disable or enable Secure Boot as needed
El secure boot It can be both a requirement (Windows 11) and a hindrance (in some problematic updates). Microsoft has documented cases where temporarily disabling Secure Boot helps complete the update, especially when combined with corrupted Windows Update files.
El general procedure is
- Walk into BIOS / UEFI when starting up (F2, Delete, F10 key… it depends on the manufacturer).
- Locate the option to Secure Boot and set it to Disabled (or Enabled, if you're going to comply with Windows 11).
- Save changes, exit, and repeat the update.
Upon successful completion of the installation, it is recommended return to the secure settings that you tap (for example, enable Secure Boot if you are using Windows 11 on a compatible computer).
Common related errors: 0xC1900101, 0x80070002 and others
Along with the failure in the SAFE_OS phase, the following often appear other error codes which help guide the diagnosis. Some of the most commonly viewed are:
- 0xC1900101Classic driver error. Solution: Update drivers, disconnect external devices, check GPU, storage, and network.
- 0xC1900200 / 0xC1900202The PC does not meet the minimum hardware requirements. The only option here is update components (RAM, CPU, etc.).
- 0xC1900208 / 0x4000CThere is software installed that is incompatible with the update (antivirus, very old utilities). Remove problematic programs.
- 0 x 80070002The system cannot find the specified file; this is very common with multiple disks connected. Disconnect secondary disks and leave only the disk where you will install Windows.
- 0x80080005 – 0x90018Errors occurred while creating the USB drive with the Media Creation Tool. Run it as administrator or download the ISO and burn it with another tool.
- 0 x 80070070: insufficient disk space. Free up space or extend the system partition.
Additionally, when you suspect corrupted files on the system or in Windows Update, It is good practice to launch from a CMD with administrator privileges the following checks:
- chkdsk / f C: to check for errors on the system disk.
- DISM.exe / Online / Cleanup-image / RestoreHealth to repair the Windows image.
These tools help to leave the system in a more... clean and stable in order to attempt the update again.
What to do if you upgrade from a very old version of Windows (example: from Windows 7 to 10)
When trying to make the leap from an older system (for example, a laptop with Windows 7 pre-installed(like a Samsung RV511 with an i5 and 4 GB of RAM) to Windows 10 while maintaining programs and data, several complicated factors come into play:
- Very old drivers or drivers without official support for Windows 10.
- Older software that may be incompatible.
- Partitions with years of use, full of remnants of previous installations.
If in such a case, after attempting to install Windows 10 "on top of" the existing installation, the process hangs and ends up returning an error message. SAFE_OS error during BOOT Time and again, there are several strategies:
- Apply all the recommendations seen: Disconnect peripherals, automatic services, updated drivers, DISM, chkdsk, etc.
- Remove or uninstall suspicious drivers before updating (GPU, card reader, aggressive security software).
- If after several attempts it continues to fail, consider a clean installation of Windows 10, by backing up data and reinstalling programs from scratch.
Although on-site upgrades are more convenient, on very old equipment or with heavily loaded systems, sometimes the most stable and least problematic option in the long run is format and start with a new Windows, always after making sure that your license (digital or purchased) is correctly associated.
Errors when applying patches and cumulative updates
Not everyone encounters the SAFE_OS phase when installing from scratch: many see similar problems when trying to apply cumulative updates for Windows 10 or 11 via Windows Update. The most typical symptoms are:
- Messages like “The updates could not be completed. Undoing changes".
- Codes 0x80073712, 0x80200056, 0xc1900223, 0xC1900107…
recommendations In these cases they go through:
- Check the update history and note the code of the one that fails.
- Run the repair tools Windows Update from Microsoft.
- Clean the folder C: \ Windows \ SoftwareDistribution \ Download to remove corrupted downloads.
- Use DISM and the System File Checker (sfc /scannow).
- Uninstall recent updates if the problem started right after a specific one (for example, if a Login error after update).
On systems where updates are frequent, some users opt for temporarily pause updates from Windows Update for a few days, allowing Microsoft to fix initial bugs before installing them.
Preventive measures to minimize failures when updating
To avoid experiencing each major update as a lottery, It is worth taking some measures before you start installing new versions of Windows:
- Always keep sufficient free space (minimum 10-15% of the system unit).
- Have one on hand recent backup of important data, either with built-in Windows tools or with third-party solutions.
- Avoid accumulating junk software and very old programs that could cause incompatibilities.
- Check the status of the disk (chkdsk) and the most critical controllers from time to time.
- Never interrupt the update process by turning off or restarting your PC unless absolutely necessary.
With all this in mind, the famous message that The installation has failed in the SAFE_OS phase It ceases to be a death sentence and becomes just another Windows problem that, with patience, can be resolved. By addressing the key issues (peripherals, drivers, BIOS/UEFI, disk space, and the health of Windows Update) and repeating the installation with the cleanest and simplest system possible, the chances of completing the update without having to format or lose data increase significantly. Share this information so other users can learn the details of this error.