Questions[single-user](ubuntu)

I am using 19.10 upgraded from 19.04. The OS was a virtual machine image downloaded from https://www.osboxes.org/ubuntu/ the downloaded image was 19.04 which I had upgraded to 19.10 There were some problems during upgrade which I managed to solve.ubuntu stuck on boot in after upgrade to 19.10 from 19.04 in vmware [end kernel panic not syncing:VFS:unable to mount root fs on block (0,0)]

The default passwords were https://www.osboxes.org/faq/what-are-the-credentials-for-virtual-machine-image/ I had a default administrator account osboxes.org which I removed and created a new user called debian (this I did on 19.10 after upgrading from 19.04) During the use of machines before upgrade I probably had reset the root password which I forgot and after upgrading I had deleted the original user account osboxes.org. I had created a new user username:debian I forgot its password also. So I thought of resetting root password as explained here https://md3v.com/linux-give-root-password-for-maintenance-lost-password
every thing worked perfectly I was able to reset the root password. Now when I try to login from Gnome interface as root the updated password is not accepted as a result I am locked out. How can I get out of this situation I don't see any error messages also. I set my root password as debian and this is not working.

Today I try to use the way that I've known for several years to enter the Single User mode: enter the edit mode of grub and add single at the end of line of kernel and type F10.

I thought I could enter the Single User mode without typing password but to my surprise, it asked me to type the root password. I don't know why because I always used this way to rescue my linux system, for example, if I lost the root password, I could use this way to make a new root password.

But now things changed...

So Ubuntu has blocked this non-password single user mode?