We couldn’t create a new partition Windows 10 install

Before we start this process make sure that you don’t have any SD Cards connected to your PC.

We have to warn you that this process will delete all files from your hard drive, so if you’re planning to use it, make sure you create a backup beforehand. To run diskpart, follow these steps:

1. From the installation window with the error press Shift + F10 to open the command prompt
2. When Command Prompt opens, enter diskpart.
3. Now enter list disk. You should see the list of all hard drives connected to your computer.
4. Find the number that represents your hard drive and enter select disk 0 (we used 0 as an example, so be sure to replace 0 with a number that matches your hard drive).
5. Enter the following lines and press Enter after each line:
   • clean
   • create partition primary
   • active
   • format fs=ntfs quick
   • assign
6. Enter exit in order to close Command Prompt.
7. Continue with the installation process.

As already mentioned, this solution will delete all files on your selected hard drive, so use it on a new computer that doesn’t have any files on it, or only if you have a backup available.

Modified but originally taken from https://windowsreport.com/we-couldnt-create-a-new-partition/