do-release-upgrade from 18.04 to 20.04 failed

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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Bobby Iliev
Site Moderator
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June 21, 2020
Accepted 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:
  1. sudo apt update
  • Next, upgrade installed packages to their latest available versions:
  1. 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! Regards, Bobby

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