I recently upgraded my work laptop from Windows 8.1 to Windows 10 build 9926. The upgrade went quite smoothly and there was no issues during or even after the upgrade. I didn’t have to enter a new product key for Windows 10. The same products key of Windows 8.1 was used for Windows 10 upgrade.
Things went smooth until the next upgrades of Windows 10 build 10041 and build 10049. Windows Update would download the updates successfully and start installing the updates after restart. But the update would hang in the middle and I would need to restart the PC after sometime. After restart, Windows would restore to the previous build of Windows 10.
The error message would read like this:
Couldn’t update to Windows 10 Technical Preview
Sorry, we couldn’t complete the update to Windows 10 Technical Preview. We’ve restored your previous version of Windows to this PC.
0xC1900101 – 0x2000C
There are two possible solutions that I have found out. Let’s go through each solution:
1- Make space for Windows installation in the system drive
0xC1900101 – 0x2000C may refer to a limited space issue in the system driver where Windows is installed. Make sure you have sufficient space in your C drive (system drive). If we look at Windows 10 requirements, the space needed for Windows 10 32-bit clean installation is 16 GB while 20 GB is needed for 64-bit installation. Although these requirements are for clean installation of Windows, you should have at least the same amount of free space in your system drive in order for the update to be successful.
You may use utilities like CCleaner to cleanup junk and unnecessary files from the system drive.
2- Rename Windows.old folder to something else
Another reason for 0xC1900101 – 0x2000C error could be the Windows.old folder. If you have a folder named Windows.old in your system drive (C drive), you will need to delete it before upgrading Windows 10 using Windows update.
If you can’t find Windows.old folder, you should run CCleaner and check Old Windows Installation under Advanced and run the cleanup. This will make sure that all the old Windows installations files will be removed from the system. This will clear some space in the system drive as well as making way for Windows 10 update to be installed successfully.
Please note that Windows.old folder contains all the files of your previous Operating System. If you need those files, just rename the Windows.old folder to something else.
Please let me know if you were successful in solving 0xC1900101 – 0x2000C error using the fixes and solutions given in this article. These fixes also apply to Windows 8 and Windows 8.1 issues with the same error code.