Recovering a Windows 10 password when the partition is read-only

Start booting Windows and press F8 during the boot process. Select to discard hibernation data and start Windows normally, then shut it down. That should remove hibernation data and make the partition read-write again.

As a last resort, boot Windows till the password prompt, wait for the HDD to settle down then switch the laptop off with the power button.

Then boot into Debian and try the chntpw trick once more.

There is an easy fix for this problem.

Boot Windows, then click on the screen to access the login window.

In the lower right corner, click the Power icon, then click restart. No hibernation data is written by Windows when restarted, only when shut down.

Boot into Linux and go ahead with clearing your Windows password.

Once you're able to log into Windows, disable Fast Startup so you won't run into this problem in the future. See https://www.windowscentral.com/how-disable-windows-10-fast-startup for how-to details.

By the way, as mentioned in the article, you will probably have to disable Fast Startup again after each Windows "edition" update.

There is another option. Before you ran chntpw in Debian, you had to mount the drive with a command like sudo ntfs-3g /dev/sda3 /media/sda3. (That assumes that you already created /media/sda3.) If you had used the remove_hiberfile option, such as sudo ntfs-3g -o remove_hiberfile /dev/sda3 /media/sda3, then ntfs-3g would have deleted the Windows hibernation file hiberfil.sys for you, which would have solved your problem.

Please note that using an external program to delete the Windows hibernation file is dangerous, because any data saved only to the hibernation file will be lost. This procedure is only to be done as a last resort.