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I am a Ubuntu newbie. I am running Ubuntu 16.04. Until yesterday my computer was fine. But today it got stuck in a login loop. I enter my username and password, it lets me to log in, but after a few seconds, it goes back to the log in screen. It keeps repeating forever. I went through the Ubuntu forums. They have suggested to login using Ctrl+Alt+f1 and then run mv .Xauthority Xauthority.backup. The problem is when I executed Ctrl+Alt+f1, a progress bar is shown forever and it never opens the terminal. I am not sure what to do next. Any help is greatly appreciated.

Thanks

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  • The most common reason I've had for login-loop is a lack of space in $HOME, as the GUI requires temporary work files to be created, and login will fair (ie. you're logged out without message) if insufficient space exists in $HOME to create said files). I don't follow the progress-bar though; are you able to login via text terminal? Did you check you have disk space etc? ($HOME refers to /home/$USER where $USER is your user id)
    – guiverc
    Mar 10 '20 at 2:43
  • The Ctrl+Alt+f1 also stuck in an infinite loop. It never opened the terminal.
    – Massey
    Mar 10 '20 at 2:49
  • Did you try another combination, eg. I usually opt for Ctrl+Alt+F4, F3 etc as I've too had issues where ctrl+alt+F1 & f7 don't do what you expect them to (f1 becomes f2, f7 becomes f8)
    – guiverc
    Mar 10 '20 at 2:52
  • I tried all the combinations but no luck!
    – Massey
    Mar 10 '20 at 12:13
  • Boot to Recovery Mode from the GRUB menu. Get to the root # prompt and type sudo ls -al /home/your_username/.*thority. Edit that output into your question. Start comments to me with @heynnema or I may miss them.
    – heynnema
    Mar 10 '20 at 22:23
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If you still cannot bring up a terminal even with ctrl+alt+f1, it would be worth preparing a Live USB if you have access to another computer, booting from that, and checking that there is enough space, as @guiverc suggests.

Once you boot off the live USB, or manage to boot into a command line, use

sudo blkid

To find out the layout of your disks. Once you identify a likely suspect, for example /dev/sda, you can mount it using:

sudo mount /dev/sda /mnt

Once it's mounted, take a peek inside it to see which drive it is, and use:

df -h

To see what the capacity of the drive is (it will be the one that it says is mounted in /mnt).

Work your way though your drives/partitions until you see whether one of them (as @guiverc says, probably the one housing your /home folder, is full.

If you know which drive you home folder is in, go ahead and mount it as above, using the actual drive name, and use df -h to see whether it's full.

If they are, make space by clearing your caches. They usually are in .cache. The contents of this folder are safe to remove.

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  • There is enough space. During one of the login loops, I have managed to check the hard drive. It has used 200 GB and 700 GB is free.
    – Massey
    Mar 10 '20 at 12:15
  • Yes, but how is your system laid out? Is the whole disk one ext4 partition or do you have multiples? Do you use LVM for a separate /home volume?
    – Kurankat
    Mar 10 '20 at 21:28

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