do-release-upgrade from 18.04 to 20.04 failed

Posted June 19, 2020 7.4k views
Ubuntu 18.04

Upgraded successfully from 16.04 to 18.04, then followed the tutorial for upgrade from 18.04 to 20.04.
do-release-upgrade fails with “ERROR doUpdate() failed completely”.
Lots of “ERROR IOError/SystemError”, but this one caught my eye:

ERROR IOError/SystemError in cache.update(): 'E:Failed to fetch  File has unexpected size (200 != 135). Mirror sync in progress? [IP: 443]

Where to start debugging this problem?

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1 answer

Hi there @mike426137,

I just tested the upgrade process with do-release-upgrade -d and it worked as expected.

I would recommend trying to run the following:

  • Begin by updating the package list:
  • sudo apt update
  • Next, upgrade installed packages to their latest available versions:
  • sudo apt upgrade
  • Finally run the dist upgrade command again.

If you get any errors again, feel free to share them here so that I could advise you further.

Hope that this helps!