NoMachine & Samba login trouble

[RobertGM]

At present I have two computers running remote desktop application NoMachine.
Coincidentally, the computers are connected for file sharing with Samba;
they, in turn, are connected to two other computers, also using Samba.
While I cannot login to the computer (which I was viewing from my main computer), the other computers can see and access folders and files on it.
Here's what happened:
I rebooted the computer I was viewing while I was viewing it for the first time with NoMachine. (Apparently, that should not be done.)
Just prior to this, I had added a Samba user for file transfer purposes; so a second person could backup files on the computer in question.
Now that username and name show up (as separate boxes) along with my own and a couple of other options, including Samba guest account.
I have never seen this screen before. And the Mint 19.3 computer in question was set to auto login, which it previously did.
I have unplugged and restarted it, to no avail.
This Topic derives from these two:
local network not working
share desktop mint 20.1 & mint 19.3

[AndyMH]

Booted two laptops (both LM20.1), used nomachine on #1 to remote into #2. Via nomachine from #1 told #2 to reboot. Connection to #2 dropped as expected. #2 rebooted normally, grub menu, then login window, entered password, all normal. Not convinced that nomachine is your problem.

What exactly happens when you try to boot the troublesome PC - error messages, what appears on screen?

[RobertGM]

Thanks for the reply AndyMH.
This is what I see:

I have not seen this login screen before.
When I select main user and enter the password I get "invalid password".
If I select main user's full name and enter the password, the screen refreshes but does not login. The password box remains empty.
I have had trouble with keyboard layouts on a couple of Mint 20 computers. For example typing
"
displays
@ (and vice versa) plus some letters change to numbers until I fiddle with the keyboard selection. I wonder if this is what's happening on this computer. Although there was never a problem before. But that is why I selected the onscreen keyboard. But, it doesn't matter if I use it or the actual keyboard, the results are the same.

[AndyMH]

I will set auto login and repeat what I did before and see what happens.

Are you sure you got the password correct? One reason why I never enable auto login = too much risk of me forgetting what it was. Apologies in advance for the question - is CAPS LOCK off?

[RobertGM]

Are you sure you got the password correct?

Yes. Although when setting up the second user I had to add an extra character. However, I tried both the main user's original pw and one with the extra character. Neither work.

is CAPS LOCK off?

So far as I know. I did tap on CAPS LOCK on the keyboard and that causes the onscreen keyboard to change. And I typed the password with CAP LOCK on and with it off to double check. Neither work. Unfortunately, I cannot see what is being typed.

[AndyMH]

Just done what I said I'd do - set laptop #2 to auto login - rebooted and it booted as normal. Then used nomachine on laptop #1 to reboot it. All worked as it should.

The only thing different from normal manual login was a window after boot saying "Authentication required: the login keyring did not get unlocked when you logged into your computer" and asking for my password.

So whatever the problem is, it was not caused by nomachine.

Suggest you change the title of the topic to something along the lines of mint will not accept password.

This might help (and it has a few links to other sites if it doesn't work);
https://community.linuxmint.com/tutorial/view/339

Your other alternative, restore from a timeshift snapshot if you have one.

[AndyMH]

Looking at another thread you may have run out of space on your / partition.
viewtopic.php?f=46&t=349514

[RobertGM]

Thanks AndyMH.
I checked from a Live Boot DVD. There is 21 GB of free space on that partition.
Something that puzzles me is why am I getting a Samba login screen?
Having watched a little more closely, during a regular boot, the computer displays the computer name briefly (in the upper left corner) and then completes the reboot process. However, rather than displaying the desktop, I get the Samba login screen.
I have searched "Samba login" and get no hits that resemble what's happening here.

[RobertGM]

I have a Snapshot of the operating system. Does it have to be copied to a USB stick?

[AndyMH]

If you mean timeshift, no. Just boot from your mint install stick and run timeshift from that - point it at the partition where your snapshot is and it should restore.

[RobertGM]

Would that it were so simple.
The timeshift window says (in a band across the bottom):
Live USB Mode (Restore only)
No snapshots found.

When I select "Browse", at the top of the window, a folder opens where the snapshot is.
It says "Elevated privileges" across the red band at the top.
I cannot select the folder.
Double clicking on it opens the folder but still nothing is selectable.
And the contents are localhost (folder) and three files: exclude.list | rsync-log | rsync-log-changes.

[AndyMH]

Go into settings and then the location tab.

Click on the partition where the snapshot was saved.

[RobertGM]

I did that.

[RobertGM]

Should I copy the Timeshift folder to a USB drive?
If so, does the USB drive have to be blank otherwise?

[AndyMH]

No, once you point timeshift at the partition with your snapshots, it should find it and show it in the main window. If it hasn't I'm guessing something is broken. Hence my link to how to change your password. Other than that, I'm out of ideas.

[RobertGM]

Before another attempt at this, is it fair to ask where the (I think) Samba login screen comes from?
As I mentioned, the computer appeared to auto login then the screenshot I posted earlier.
What is that?
I'm also wondering if I should purge Samba and reboot?

[AndyMH]

No idea, can you post a screenshot of it, might provide some clues? Hopefully someone else will join the conversation.

Was it a 'normal' install, or did you encrypt it - just trying to think of reasons why it may have gone sideways?

EDIT - I think the screenshot is the one you posted earlier showing a samba guest account - not seen that before.

EDIT2 - with the problem PC at the login screen, can you remote into it from another PC using nomachine? I'm expecting no, but chasing straws.

I'm also wondering if I should purge Samba and reboot?

If you can't login, how were you hoping to purge samba?

[altair4]

I'd like to help ... truly ... but the symptoms described here are alternate universe stuff to me.

If a restore from Timeshift or whatever it's called isn't possible is it inappropriate to suggest a fresh install?

[AndyMH]

I'd like to help ...

Can you read my mind? Tried to PM you earlier, thought samba = altair4, I wonder... but you have them blocked

[RobertGM]

I'm thinking there must be some way to disable Samba, temporarily, to see if NoMachine works. Then address the issue with Samba. If Samba is to blame.
While in Live mode I tried disabling Samba by renaming the smb.conf file. But my change was not saved. (I opened the folder as "root".) On reboot (to live DVD) the file still had its original name. I then moved smb.conf to a new folder and that too did not get saved.
I copied the Time Shift folder to a USB drive. However, while the folder size is the same--1.1 GB--the file count on the USB is half that of the original. There were many interruptions saying it cannot copy symlinks. Evidently that won't work.
You might be right AndyMH, a fresh install may be in order. It is, however, my original computer and I would like to keep it around for a bit yet.
Thanks for joining in altair4.