I have Dell Precision T-3620 Workstation and I have installed ubuntu 16.04 in it. It worked well for 1 day. One Day, I had to run a command on the terminal so I pressed  Ctrl + Alt + F1 before logging in. I did my work and when I restarted it, I faced a problem. When I write the password, the screen just flashes and the login screen comes again in front of me. When it asks for password, I give it. It waits for sometime and the screen bounces back to the login screen, It recognizes incorrect password and I can login through the terminal but I can't access my files and when I add the correct password, it waits and screen bounces back. Someone said to remove .Xauthority, so I pressed Ctrl + Alt + F1 and typed rm .Xauthority But it still didn't work.   Please anyone help me out.  Thanks in advance..............
917
I installed or upgraded to Ubuntu 16.04, but I'm having some problems with my graphics card.   The display is blank The display flickers Items on the screen do not display correctly Certain programs complain of graphics issues The computer boots to low-graphics mode Your specific issue may not be here, but try the solutions described in the answers anyway.   This question is very broad, but each one of these issues likely has one solution.    If you are experiencing a login loop, check the last part of my answer.    If you experience one of the listed issues and have your own solution (mine didn't work, or there's a faster way), feel free to post another POLITE answer, describing your problem and how you fixed it.    Those attempting to install Ubuntu, please refer to the section titled: If you are unable to enter a TTY or are trying to install Ubuntu.
98614
After entering an incorrect password at a login prompt, there s an approximately 3-second delay. How can I change that on a Linux system with PAM?
97926
I have a , with Ubuntu 16.04 installed.  I have recently (today) updated it(not upgraded), and afterwards it asked for a reboot, so I did that. However, after reboot it showed the login screen and mentioned connection established (for internet through Ethernet), and login password cursor was blinking during that time but after that even the cursor stopped blinking and accepting no response from keyboard or mouse. Only one option is to force shutdown. I have no idea what part of the update resulted in this.   Everything was working fine before the update. Once the Ethernet icon announcing connection has been established goes away, it takes away the blinking of the cursor, then keyboard and mouse simply won't work. I even tried connecting keyboard on other slots, but no success. Can I uninstall the last update?  NOTE:  I heard a sound from the processor when login screen comes and in between the cursor also blinks, but once this sound is over then the blinking freezes and you have to forcibly shutdown, as this is an institute computer (I took the admin privilege, headache). Now I am  really worried about it. How to fix it?  IMPROVEMENT  I did not have to go for a live USB, and I was able to go to grub I was able to go to the GRUB menu by pressing the Esc key). This what I got.      I have no idea how to go about it after that. It is saying Secure boot forbids loading module, while loading Ubuntu I did secure boot by entering a password for that.
79995
The screen lock is not working, it does not lock the screen (no password required).  I would like it to prompt for a password every time the screen locks (clock screen).  All instructions tells me to enable this in privacy but I can not enable or disable as it's grey (gray).  Ubuntu 17.10 upgraded from Ubuntu 17.04, upgraded from Ubuntu 16.10.    Any help or advise would be great as I already tried many setting and installs and removes suggested on online.
42371
This didn't start out as a problem with the login loop.  I was attempting a clean install of Ubuntu 16 and using the new feature that allows it to detect proprietary drivers for me.  I started off with   When I attempted to use the recommended Nvidia Drivers, it caused the laptop to become unstable and freeze.    I attempted the remedy from that post and it resulted in a login loop.  I have attempted   sudo mv ~/.config/dconf/user ~/.config/dconf/user.old   Tried   sudo mv ~/.Xauthority ~/.Xauthority.backup sudo service lightdm restart   I have tried locating and disabling secureboot, but there is no secureboot option in the bios.  This is an HP DV2000 series laptop.  Nothing is helping    Can someone help?  edit:  Guest session does the same loop.  /var/log/Xorg.0.log shows a lot of stuff, but I took a pic of what seems relevant   Thing is the driver I first tried that started this mess was 304 drivers and the 364 drivers were supposed to be the fix according to other posts.  More editing:  I purged the nvidia files and it came back to a blank desktop w/o the interfaces so I right clicked and restored a backup.. The sidebar came back and it was running gallium.  I restarted and its the blank purple screen again.  I am thinking of just reinstalling and not using nvidia drivers.  The software center is telling me I have a presario and i should use 304 drivers.  Its not a presario. =(  At least the software center provides a suggestion for the coprocessor driver which is nice.
14451
So I just installed Ubuntu 16.04 on my Dell XPS 13. When I get to the login screen it starts at 3200x1800 for a quick second, then I get a way lower resolution like 800x600 but as soon as I login it adjusts to 3200x1800. How would I get 3200x1800 permanently on my login screen? I didn't have this issue on 14.04.
8273
I notice a weird (well, according to me) thing about passwords. For example, if I type an incorrect password during login, there will be a few seconds' delay before the system tells me so. When I try to sudo with a wrong password I would also have to wait before the shell says "Sorry, try again".  I wonder why it takes so long to "recognize" an incorrect password? This has been seen on several distributions I use (and even OSX), so I think it's not a distribution specific thing.
1378
My Ubuntu is stuck in a login loop when trying to enter my desktop. When I login, the screen gets black and soon after that the login screen comes back.   I've read that the problem might be caused by an error depending on the graphics, here's my graphics card: ATI Radeon 7670M
88002
I am horribly impatient and can't stand the (for me subjectively long) delay of around 2 seconds after entering an incorrect password in the login screen or also as sudo password, before I can retry typing it correctly.  Is there a way to modify the delay and reduce it to around half a second or turn it completely off, both for sudo and the login screen?   The optimal solution would include a longer delay after maybe 3 or 5 incorrect passwords, to still prevent brute-forcing.  PS: I am currently using vanilla Ubuntu 16.04 with Unity Desktop and lightdm.
86791
So i installed Ubuntu 18.10 fresh install and i did have the normal new login screen of ubuntu gdm3. Ive been downloading gnome themes and i noticed after i did everything(idk if its from installing new themes) when locking the computer i still get the normal lock screen  And when i slide it up i get the stamdart login screen:   Lock screen  Login screen    But now it gets weird when i click on "Log in as another user" i get a new different type of log in screen, which comes when booting into ubuntu after the logo loading screen too(on this login screen the tap-to-click also doesnt work!):   2nd login screen    EDIT: Im sorry i forgot to add a question  - What is this(is this normal?) and how to set it back to default?  Added theme:  Named "flat remix"   I would be happy for your help Thanks Best Regards!
87434
There's been one problem I've had since I installed Ubuntu to run alongside Windows, I assume this would also be the same if it was installed to replace the other operating system as well, the installer prompts you to create a password upon typing in the user account name and if you don't put in a password and just put in the user account name, it ends up saying to create a password. My comparison is in Windows and Mac OS X, you are never forced to create a password.  If you remove the password on your Admin account in System Settings > User Accounts, you won't be able to authenticate whenever you try to install something, because it requests for a password and putting in no password at all isn't going to work, it will just act as if you put in an invalid password. This is what I call "getting locked out of privileges".  I'm finding the "Authenticate" window that comes up whenever you install something or accessing somewhere a nuisance, 'cause it always requests for your password.  So my question is - Why does Ubuntu force users to create a password upon installation?
58117
Why does Ubuntu not allow the GUI users to login as root at the time of system start up like administrator in Windows?  Why they are restricting us to login only through the terminal?
59438
After upgrading from 12.04 to 14.04 I could log in to my X session (albeit with really low graphics). While trying to fix the graphics, I managed to break the X session.  Now, after typing my password in the unity-greeter, the items disappear and I can only see the desktop background and the pointer. This happens for every user. I can still log in in tty's. How can I solve this?  Also, I cannot seem to be able to install nvidia-current as it tries to install nvidia-304 and it depends on old video-abi libraries. Is there a way to tell the package manager that nvidia-current should use a newer version?
21676
I'm about to config my new fantastic T460s with Ubuntu 16.04 (because of Skylake Kernel issue I've to chose such new version) I tried to use my fingerprint sensor which is 138a:0090 (lusb) Fingerprint Gui doesn't recognize the device which is no wonder, because it is not on the compatibility list of it. Do I've to wait for a driver or is there something I can do about this?  Thanks a lot :)
38697
I have a problem with Ubuntu 13.04.  I cannot log in to my account. I put the right password but there is an endless loop. (if i put wrong pass, it says "Invalid password..."). Also, it doesnt show the small drop down menu with choices "Gnome fallback, Default, etc.."  If i login as guest, the desktop is clear, no bars, no menus, anything. Just right clicks works only.  I have already try  solution ( chown username:username .Xauthority ) but there is no "Xauthority" at ubuntu 13.04. (?)  Is the problem about lightdm? Also, i tried sudo dpkg-reconfigure lightdm but it soesn't work.  I use the recovery mode (root command shell or something like this) in order to try the above commands.  Has anyone a solution?  Thank you.
76190
What happened  I was working on my laptop while it upgraded from 15.10 to 16.04 (which I admit was a mistake) when suddenly the Unity overlay disappeared and the only thing on screen was the Firefox browser window. I switched to a new terminal, logged in and tried to run sudo service lightdm restart but instead of restarting correctly, the screen started turning on and off repeatedly, which freaked me out, so I physically turned off the PC.  Long story short: I forced a shutdown halfway through the Ubuntu upgrade.  Ever since, any attempts of logging in normally have been met with a solid black screen and the idle whirring of the CPU fan.  What I have tried  I have tried the recovery mode boot up, but no luck (The log does greet "Welcome to Ubuntu 16.04 LTS!"). I tried out each option that seemed useful:   dpkg goes through the packages as advertised, but strangely enough it always locks up on some Braille package until I do Ctrl+C, at which moment it spouts some error messages and then I think throws me into the normal boot. failsafeX results in a similar situation to the normal boot: a black void. fsck says the single partition I have is a-ok. grub seems to get a bunch of stuff. Don't know if it searches locally or fetches from the internet. network didn't work I think.   I tried following  but couldn't do the sudo part because the filesystem was mounted as readonly. So I ran fsck which mounts as RW and tried again.   This time, after running apt-get autoremove it went through many packages (Setting up foobar (X.Y.ZubuntuN) ...), sometimes installing packages, which I assume is the usual behavior. One thing to note though is it kept getting stuck several times, so I had to Ctrl+C it out of processing the current package. It finally ended on "Processing was halted because there were too many errors.".  While  seems to mention some of the graphics problems I've been experiencing... I have Intel HD Graphics, not Nvidia. I'll keep looking into it.
119559
how can I reset a lost administrative password ,considering that Ubuntu and windows7 are both installed on the computer , considering also that "Boot up the machine,and after the BIOS screen, hold down the left Shift key." didn't logged me to any thing, just continue the loading of the system as normal??