Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I was upgrading my ubuntu 12.10 to 13.04, using following command:

sudo do-release-upgrade

everything is OK until I get following error message :

    Could not download the upgrades 

The upgrade has aborted. Please check your Internet connection or 
installation media and try again. All files downloaded so far have 
been kept. 

Failed to fetch 
Size mismatch 
Failed to fetch 
Size mismatch 

Restoring original system state

Reading package lists... Done    
Building dependency tree          
Reading state information... Done
Building data structures... Done

what should I do for this?

share|improve this question

Have you tried doing it via the GUI it may be easier?

Make sure you backup, it may cause you some frustration later on if not.

Start off with do-release-upgrade -c

if this fails You may need to install the update-manager-core package if your distro is no longer supported.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.