I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.

I just tried to upload a screen shot but since I'm new it won't allow me to. I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:

An unresolvable problem occured while initializing the package information
Please report t:his bug against the 'update-manager' package and include the
following error message:
'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse) 
E: The list of sources could not be read., 
E: The package list of status file could not be parsed or opened.

How do I report bugs? What can be done about this. I have searched and everything everyone says to do leads me back to the same line error message.

So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.

  • 9
    Can you add the content of your /etc/apt/sources.list between lines 67 and 69??? Commented Jun 17, 2012 at 17:10
  • 2
    Edit your question to include the output of the command cat /etc/apt/sources.list. And no you don't need to wipe out everything. It is very easy problem (from my experience)
    – Anwar
    Commented Jun 17, 2012 at 17:14
  • You don't need rep points to post the output. However, you do need to format the output as code or it will not let you post the output because you don't have enough rep points to post multiple links. Edit the question and paste the output and then highlight the output and then press CTRL+K to format the output as code and then save the changes.
    – mchid
    Commented Feb 6, 2019 at 16:40

9 Answers 9


Some lines are broken in your sources.list file (or another *.list file in sources.list.d/).

Edit the file mentioned in the error to fix the broken lines.

  1. To do this, run this command (press Ctrl+Alt+T to open a Terminal):

    sudo -H gedit /etc/apt/sources.list

    Or, instead of Gedit (which not all Ubuntu systems have), you might prefer to open the file an a terminal-based text editor:

    sudoedit /etc/apt/sources.list

    If necessary, replace /etc/apt/sources.list with another file name, i.e., the path to some file inside /etc/apt/sources.list.d/.

  2. Find the lines which are incorrectly formatted (refer to the error for a line number, then look around that point). These are examples of correctly formatted lines:

    # Comment, marked by a line starting with '#'
    deb http://site.example.com/debian distribution component1 component2 component3
    deb-src http://site.example.com/debian distribution component1 component2 component3

    The URL, distribution and components will be different. It does not necessarily have to have 3 components.

    Anything which doesn't fit this format is incorrect.

  3. Save the file and quit the text editor. Then run this command in a Terminal window:

    sudo apt-get update

Assuming there are no errors, the problem is now fixed. You should be able to run the Sofware Center.

However, while some problems with the Software Center can be solved by reinstalling the software-center package, most cannot, so it's possible your original problem will remain. If that is the case, you can post a new question to get help with it.

  • I think that sometimes for Debian based distros you need ./ at the end of the line as in this example Commented Mar 14, 2018 at 16:17

Quick Method

A workaround for this problem can be building the sources.list entry from scratch. For trusty:

deb http://archive.ubuntu.com/ubuntu precise main universe restricted multiverse
deb-src http://archive.ubuntu.com/ubuntu precise universe main multiverse restricted

deb http://security.ubuntu.com/ubuntu/ precise-security universe main multiverse restricted
deb http://archive.ubuntu.com/ubuntu precise-updates universe main multiverse restricted
deb http://archive.ubuntu.com/ubuntu precise-backports universe main multiverse restricted

# deb http://archive.canonical.com/ubuntu precise partner
# deb-src http://archive.canonical.com/ubuntu precise partner

# deb http://extras.ubuntu.com/ubuntu precise main
# deb-src http://extras.ubuntu.com/ubuntu precise main
  • Copy the above content (in gray box) and open the sources.list file as root.

    Typing sudo -H gedit /etc/apt/sources.list this in a terminal and hitting Enter will do the job.

  • Then paste the copied content in the sources.list - note you probably will need to replace precise with the codename representing your Ubuntu version (lsb_release --codename) - e.g. trusty for 14.04. Then save and close gedit.

  • Then do sudo apt-get update and you will see that the repository list is updated.

Explanation: Here we are completely replacing the content with another sources.list file with repository entry from Main Server. If you want to use your local server for sources.list see the method below.

Recommended Method

Go to the Ubuntu sources list generator site.

  • Select your country.
  • Select your desired branches, such as Main, Restricted, Multiverse, Universe.
  • Select desired update list, -
  • Select any third party repository list if you wish.
  • Click Generate list at the bottom of the page, you will be given a list with repositories.
  • Copy that list and replace with sources.list file you have.

You are done. (I hope this will help.)

  • 5
    Strange that this was not accepted!! A quick fix, comment the problematic line in /etc/apt/sources.list by adding ## as first characters in the line. Then try sudo apt-get update. Commented Sep 12, 2012 at 7:32
  • 4
    Maybe it wasn't accepted because the user may have other repos enabled and they would lose them if they did this. For example, most users of VirtualBox get it from Oracle's repo. Also, Oracle uses different package names in there repos than Ubuntu does in theirs. Therefore, if I installed VirtualBox with Oracle's repo and followed this guide, I would sit at the same version of VirtualBox all of the time and never get an update. Never.
    – John Scott
    Commented Jan 3, 2015 at 18:30
  • @FuzzyToothpaste they will not lose them if they did this. It only removes the duplicate entries. Your example scenario has nothing to do with this problem
    – Anwar
    Commented Jan 4, 2015 at 2:36
  • 1
    When using Ubuntu source list generator site to generate new sources.list file do not forget to update GPG keys. Otherwise issue may persist Commented Oct 10, 2017 at 18:22
  • Ubuntu sources list generator site seems abandoned since 2018 Commented Apr 25, 2022 at 4:15

As you can see from the error, it says that your sources.list file has a wrong entry. This wrong entry could not be parsed. This error is not related to Software Center as such but mostly to do with apt(The package manager)

The way to solve this would be to fix the malformed line 91 entry.

If you cannot understand what is wrong with line 91, please post line 91 and I will help you out


Please paste file /etc/apt/sources.list so we can troubleshoot this problem for you. See this short tutorial answer for how to do that:

How can I easily share the output of a command or a text file with others?

This can sometimes be a very easy fix, but you must backup sources.list first since it's a critical file.

  1. Open the terminal with Ctrl+Alt+T.
  2. Type/paste: sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup (this creates a backup copy)
  3. sudo sed -i -e '68d' /etc/apt/sources.list (this deletes the problematic line)
  4. sudo apt-get update (this updates the database with the hopefully-fixed file)

If you see no errors appear when you try step 4, the problem is hopefully fixed. You can exit the terminal and go back to Software Center/Update Manager and it should work.

If there is still a problem, you can restore the original file from the terminal with sudo cp /etc/apt/sources.list.backup /etc/apt/sources.list. In that case, please paste the problematic lines or even the entire file to a pastebin and then we can help out further.

  • 4
    Deleting the offending line may not be a good idea (but kudos on the advice to back things up before doing this). What if it's a repository the user needs? Also, if a long line was somehow split into two lines, you will have two malformed lines (and the procedure has to be repeated). man sources.list has a section with examples and it may be useful to ask the user to compare his lines with the examples, maybe he can determine what's wrong and fix it himself. Personally I'd wait until he posts his sources.list file.
    – roadmr
    Commented Jun 18, 2012 at 0:04
  • @roadmr: Thanks, I agree completely with all of the scenarios you posit. I just felt that newbies may not even know how to post a file, let alone specific lines from that file, unless advised how. That inspired me to write this self-QA-howto :-)
    – ish
    Commented Jun 18, 2012 at 7:45
  • @roadmr I believe you would get an error message about two malformed lines if one long line were split into two lines.
    – mchid
    Commented Sep 3, 2015 at 7:36
  • Note that if -i.backup is passed to sed instead of just -i then sed will make the backup file itself. Commented Sep 6, 2017 at 14:03

The file /etc/apt/sources.list contains the URLs of webservers and location of other sources form (e.g. cds), from which you retrieve your software and updates. It basically tells Ubuntu where to look for new Software and updates to already installed programs. The error message you got means, that somehow the file got compromised. Without knowing what the content of your file is, it is hard to know what exactly is wrong with it. So you should post the output of sudo more /etc/apt/sources.list for us to help you better.

If the file is messed up beyond repair, you can use the Ubuntu Source List Generator to generate a sources.list anew. But you should backup your old one beforehand. Also this will cause you to lose all changes you have made for your Software Sources, e.g. in Sofware Center.

The better way to fix this is letting us see whats wrong with your sources.list

Edit after you posted your sources.list:

I believe the file you posted should look like this (note the last to lines and the missing /etc/apt/sources.list in the end):

# /etc/apt/sources.list

deb http://archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse 
deb http://security.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse
deb http://archive.canonical.com/ubuntu partner
deb-src http://archive.canonical.com/ubuntu partner
  • I'll try the source list generator after I backed up my files but it would really take a while. My laptop is still on HDD so it's not that quick yet. I added my source.list to the message above.
    – Odi1215
    Commented Aug 1, 2012 at 13:30
  • It is sufficient to back up just the one file called sources.list.
    – con-f-use
    Commented Aug 1, 2012 at 13:32
  • Okay, will do. Then I'll try the source list generator?
    – Odi1215
    Commented Aug 1, 2012 at 13:35
  • Positive. That's a Yes.
    – con-f-use
    Commented Aug 1, 2012 at 13:38
  • I typed in sudo more /etc/apt/sources.list but nothing happened.
    – Odi1215
    Commented Aug 1, 2012 at 16:58

Please try to edit your sources.list file by dropping sudo gedit /etc/apt/sources.list in a terminal (your password may be asked), after which you will have the options to enable "Line Numbers" in the Menu Edit/Preferences of gEdit and clicking the "Display line numbers" checkbox, then manually go to the Line in your error e.g. 91 or by using "Search/Go to line" (Ctrl+I does the trick).

enter image description here

At the beginning of the Line 91 drop two # symbols (##) to comment on that line and this way remove it from the update process (you can also delete that line at your own risk, I suggest you a backup).

When you finish, save the file and close it down. Then open a terminal and run sudo apt-get update and see if the error still appears. If not, then try opening your update manager.

Somehow it seems that the text in the Line 91 of your sources.list file is corrupted or there is some kind of an error, which means that some software is unable to be installed/updated/upgraded.

By commenting/removing the erroneous line the software won't be installed (if not already) or won't be updated/upgraded if that's what you try. Of which I suggest you to check where is that line coming from (which software requires it) and do the proper modifications as required in order to everything run fine.


If you face any malformed line error like below, i strongly recommend you to comment out(adding # before the line) the line rather than deleting it in /etc/apt/sources.list file.

E: Malformed line 91 in source list /etc/apt/sources.list (dist parse)

From the above error, the line number 91 in /etc/apt/sources.list file is corrupted. To comment out the line number 91, you have to run the below command on terminal.

sudo sed -i '91s/\(.*\)/#\1/' /etc/apt/sources.list

91 in the above code represents the line number. Replace the number 91 in the above code with your's if you got any malformed line error.

In some cases malformed line error will also occur in a list file that was actually present inside /etc/apt/sources.list.d directory. For example,

E: Malformed line 1 in source list /etc/apt/sources.list.d/google.list (dist parse)

In this case i strongly recommend you to delete the google.list file by running sudo rm /etc/apt/sources.list.d/google.list and then add the corresponding PPA again.

Finally update all the repositories by running sudo apt-get update command on terminal. Now the error won't appears.


You have to delete the last line of this file (not the file itself, of course):


Your sources.list file has to look something like this:

# /etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse 
deb http://security.ubuntu.com/ubuntu/ precise-security main restricted universe   multiverse
deb http://archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse
deb http://archive.canonical.com/ partner
deb-src http://archive.canonical.com/ partner

Of course, just replacing your sources.list file with that text could be a very bad thing, especially if it looked quite different before. The key point is that each line starts with deb or deb-src (except for comments, which start with #).

  • 1
    @Malika Hello, I'm glad this fixed the problem. But please try to answer questions not only for the asker, but also for people who Google this question and have slight variations of the asker's problem. This probably needs a little more explanation to make it a good "general" answer. :)
    – Jjed
    Commented Sep 1, 2012 at 14:08
  • @JacobJohanEdwards I can't agree with you, because we really can't help those people who execute commands before reading the question, IMO
    – Anwar
    Commented Sep 1, 2012 at 16:20
  • 2
    @Anwar In my opinion, it is the responsibility of the answerer to (a) not answer in a way that only helps the original asker [that's too localized], (b) does not does not appropriately warn of the potential side effects of a command. A disclaimer helps.
    – Jjed
    Commented Sep 1, 2012 at 17:07

Open a terminal using CTRL+Alt+T and execute the below command to remove line 6, which is not correct form of repository source line, thus apt giving you an error about malformed line.

WARNING: Don't execute this command without reading the question first, this command will delete the line 68 of /etc/apt/sources.list file. Check whether your problem is similar and, even if it is, replace 68 with the number of the line that you need to delete.

sudo sed -i.old '68d' /etc/apt/sources.list

This command will delete the line using sed in place. It makes a backup called /etc/apt/sources.list.old. If you don't want the backup then you can use plain -i instead of -i.old.

Alternatively, you can manually delete the line with Gedit.

  • Press Alt + F2 and type gksu gedit /etc/apt/sources.list.
    (If you don't have gksu you can use sudo -H gedit.)
  • Find the corrupted /etc/apt/sources.list and remove it.
  • Save and exit Gedit.

Correct form of repository source line:

The correct format of repository source line is:

<type of repository> <location i.e URI>  <dist-name> <components i.e main, universe>

For example:

  deb http://archive.ubuntu.com/ubuntu precise main
  • Type: deb is the type of repo, it indicates it is a binary repository, not a source repository, which has type deb-scr.

  • Location: http://archive.ubuntu.com/ubuntu location of the repository

  • Dist-name: precise is the distribution name of Ubuntu release. for Ubuntu 12.04 it is precise, 11.10 is oneiric

  • Component: main is indicating the component of repository. Ubuntu repository are divided into four parts.

    1. Main - Which contains free and open source software, officially supported
    2. Universe - These softwares are not supported by Canonical, but those are maintained by the community.
    3. Restricted - These softwares are supported by Canonical, but aren't free. These are supported to provide some essential drivers
    4. Multiverse - These are also non-free softwares, and not supported by Canonical.

See this page for more information.

You can now understand that /etc/apt/sources.list is not a repository source line and hence apt-get complaining about it.

  • 1
    Hi, Anwar, this is a good answer, but it is very risk to just have a sudo sed command at the top of it. Many people with the same problem (but slightly different circumstances) will see this answer and willy-nilly run it, and potentially wreck their sources.list beyond repair. In this case a more general approach (with a text editor) might be in order.
    – Jjed
    Commented Sep 1, 2012 at 14:12

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