Error 0xC1900101 – 0x20004 is a Windows installation error which comes up when you try to upgrade to Windows 10 from Windows 8/8.1 or 7. The detailed error message indicates that “The installation failed in the SAFE_OS phase with an error during INSTALL_RECOVERY_ENVIRONMENT operation“. This error may also come up when you try and upgrade using the Media Creation Tool.
In most cases; the installation gets stuck at 25%. The reason why is related to “BIOS & SATA” settings. Before you begin; please take a back up of all your critical data either to an external USB Drive or to a Disc.
Method 1: Unhook All SATA Cables
Since the installation is done online and with the information already stored on the system; unhook the SATA Cables and if possible unplug any external devices connected as well such as your (Printer, External USB Drives or USB HUBS). Once done; re-do the installation. If it still won’t work; then proceed to Method 2 below.
If you don’t know how to unhook the cables connected then it will be a difficult guide for you. However, if you can get hold of a service manual then it will all become very easy to follow both the Method 1 and Method 2.
What i usually do when i have to look up for manual is a Google Search this way “dell 6200 service manual”, “dell latitude service manual” which brings up a lot of information to guide me perform steps.
Method 2: Reset BIOS
Resetting BIOS is easy in Desktops as compared to Laptops because of the way the hardware is enclosed. Without detailing how to open the case all you need to do is completely power it off; unplug any power cords and open the case. If you don’t know how to open it then it would be best to ask for a guide from the manufacturer or do a quick Google Search.
Once the case is opened up, locate the flat battery on the motherboard (if you have a manual) then this information will be in there. Carefully remove the battery and wait for 5 minutes. Reseat the battery back into the board and put the case back with all screws tightened.
Turn the PC on and re-do the Install.