Updates for wrong OS

[Colin Law]

On 12 November 2015 at 13:57, Wade Smart <wadesmart at gmail.com> wrote:
> On Thu, Nov 12, 2015 at 7:53 AM, Colin Law <clanlaw at gmail.com> wrote:
>> On 12 November 2015 at 13:26, Wade Smart <wadesmart at gmail.com> wrote:
>>> I downloaded Ubuntu-MATE 15.10 to install on a older laptop last week.
>>> Yesterday on my Ubuntu 14.04 machine the updater came up and said it
>>> had 268mb of updates. That is quite a lot. I clicked ok and it started to
>>> download. Now it says I have this error:
>>>
>>> CD/DVD "Ubuntu-MATE 15.10' is required. Please insert the above cd/dvd
>>> into the drive.
>>>
>>> I looked at the source list and I do not see a entry for this so Im not sure
>>> how this is happening.
>>
>> I am not sure why you say it is for the wrong OS as you say you
>> installed 15.10 and it is asking for that DVD, however to disable it
>> check in /etc/apt/sources.list.  You will probably find a line in
>> there starting deb cdrom: or something similar.  This should be
>> commented out.  Then run
>> sudo apt update
>>
>> If you have, on Mate, a graphical app that shows the s/w sources then
>> you should be able to disable it there instead.
>>
>> Colin
>
> Ill restate.
>
> Im on Ubuntu 14.04 on my computer.
> I downloaded Mate 15.10 for my older laptop.
> I used cd creator and put Mate on a thumb drive for the laptop.
> Updates for my desktop computer with 14.04 are now attempting to
> install Mate updates.

Have you got the thumb drive plugged in?  If so unplug it.
If not then it is possible that putting mate on a thumb drive may not
be all you did.
Copy/paste sources.list here for us to look at.

Also copy paste the full result from
sudo apt-get update  && sudo apt-get dist-upgrade

Colin