Ultimate Guide to Fix Ubuntu Login Loop

The Ubuntu login loop issue causes the system to return to the login screen instead of logging in and displaying the desktop. Despite inputting the correct user name and password, users are repeatedly redirected back to the login screen. This problem can be solved by checking or removing the .Xauthority file through a terminal opened with Ctrl+Alt+F3, ensuring root owns the /tmp folder, reconfiguring gdm3, and freeing up hard drive space. Although the problem has been tagged as the "Ubuntu login loop," it can occur on other distributions as well due to the large number of computers running Ubuntu Linux.

For those running Ubuntu on Xorg instead of Wayland, this fix is applicable. A display server, which handles screen drawing functionality, is used to construct what is seen in a graphical desktop environment. While Wayland has replaced Xorg as the default display server, one can still use Xorg if needed, especially for older applications that might work better with it. To log in to Ubuntu using Xorg, select "Ubuntu on Xorg" from the menu after clicking the cogged wheel icon on the login screen. This setting will persist across reboots, but if you want to switch back to Wayland, you'll need to manually change the setting back to "Ubuntu." If you're experiencing login loop issues while using Xorg, check the ownership of the ".Xauthority" file, if available.

To access the terminal screen from the login screen, simply press “Ctrl+Alt+F3”. Once you have opened the terminal screen, log in using your regular username and password. If you have an existing “.Xauthority” file, it can be found as a hidden file in your home directory. To view hidden files, use the -a option with the ls command as shown below:

ls -ahl .X*

Don't forget to keep the placeholders

in the output.

The file is currently owned by root on this computer, but it should belong to the current user. However, this is an easy issue to resolve. By using the chown command and replacing "dave" with your own username, you can set yourself as the owner.

sudo chown dave:dave .Xauthority

After executing the command, use the ls command to confirm that you are now the owner and group owner of the file.

Ensure that you are the owner of the file called “.ICEauthority”. In case you do not have this file on your computer, you can use the command sudo chown dave:dave .ICEauthority in the same format as before. After this, reboot your system by typing “reboot” and pressing Enter. Once your system is back up, try logging in again. If taking ownership of the “.Xauthority” file did not resolve the issue, consider removing and recreating it. To do this, open a terminal window at the login screen by pressing “Ctrl+Alt+F3” and use the rm command to delete the file.

rm .Xauthority

Using the startx command to try to start an X desktop session forces a new “.Xauthority” file to be created.

startx

Reboot and try to log in.

The proper permissions on the "/tmp" directory are crucial for the smooth functioning of processes that use it to store temporary files. If the permissions become overly restrictive, it can adversely affect those processes. To verify if the permissions are correct, open a terminal screen and use the "ls" command on the "/tmp" directory. To do this, press Ctrl+Alt+F3 at the login screen and log in with your usual credentials. Ideally, the "/tmp" directory should be owned by root, and the root user, members of the root group, and all other users should have read, write, and execute permissions. The only restriction is that the "others" group, which includes everyone else but root and processes owned by root, can only change files that they have created themselves. To check the permissions, use the following command: "cd / && ls -ahld tmp".

The permissions for the directory “/tmp” are listed as drwxrwxrwt, with both the owner and group owner being “root.” The d in the permissions string indicates that this is a directory. The owner and group owner both have read, write, and execute permissions, denoted by the rwx characters following the d.

Other users have read, write, and execute permissions for files, but they can only modify or remove the files they have created. To ensure this, the "sticky bit" (represented by the letter "t") is used. If the permissions are different, you can use the chmod command to change them by entering:

sudo chmod 1777 /tmp

Check the permissions by running the command:

ls -ahld tmp

Finally, reboot the system and attempt to log in again.

Note: The output must always include the placeholder

.

Ubuntu's default display manager is gdm3, responsible for handling graphical login screens and servers. If you are experiencing a login loop problem, try refreshing gdm3. To do this, open a terminal window with "Ctrl+Alt+F3" at the login screen and use the dpkg-reconfigure command. This command ensures that all necessary files are present and dependencies are met. After running the command, gdm3 should be in the same state as if it were freshly installed.

Restart your computer and log in to check if your problem has been resolved.

This method involves completely removing gdm3 from your system and then reinstalling it. While it may take more time than the previous step, it has been proven to be effective when other solutions fail.

To do this, open the terminal and enter the following commands:

sudo apt purge gdm3

sudo apt install gdm3

Reinstalling gdm3

If you're experiencing issues with your computer, try rebooting to see if it solves the problem. However, if you're running out of hard drive space, simply rebooting won't help. This is because having insufficient hard drive space can prevent the system from creating temporary files, even if you have the correct permissions on "/tmp". To check your hard drive capacity and free space, open a terminal screen from the login screen and use the "df" command. You can also use the "du" command to see what is taking up space. Just remember to use the "-h" option when using "df" to display the figures in the most appropriate units.

The space usage of the root file system can be checked by using the command df -h. The “Use%” column displays the percentage of space utilized, while the “Used” and “Available” columns show the actual values. Currently, the root file system is mounted on “/dev/sda” with 84% of the drive capacity used. In case of investigating a hard drive with limited space, the command du can be used to identify the space-consuming files. To sort the output in descending order, we can use the -h (human-readable) and -s (summary) options with du, and then pipe the output into sort command with -h (sort human-readable values) and -r (reverse sort) options. This will provide us with a sorted list, with the largest consumers of hard drive storage displayed at the top of the list.

By using the command "du -hs * | sort -hr," we can determine that the largest directory is "Pictures." To further investigate, we can modify the command to focus solely on the "Pictures" directory and display the top 5 largest directories within it using "du -hs ~/Pictures/* | sort -hr | head -5." This method allows us to easily identify the directories taking up the most space and transfer them to other storage devices to free up valuable hard drive space.