The upgrader (do-release-upgrade) says it cannot do the upgrade, after "calculating upgrade".
It tells me to file a bug, and the bug-reporter then hangs. I press control-C and somehow it continues. Then I get a "firefox" window that doesn't work.
Anyway. The error message ("cannot perform upgrade") is not helpful in helping me solve the problem.
I had a PPA installed, I guessed that might be the problem, removed it from my sources.list. But the error persists.
I can hack a kernel, I can write/maintain Linux packages. But if the error is of the form: "cannot do X" I can't start looking for the cause.
A thread on askubuntu marked as "solved" suggested just changing the references to the old distro's name to the new distro's name in apt/sources.list . I did that, and now it's upgrading. If this works, why can't do-release-upgrade do what it is supposed to do?
lsb_release -rd
already says:
Description: Ubuntu 15.04
Release: 15.04
but I'm upgrading from 14.10.
---
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CrashDB: ubuntu
DistroRelease: Ubuntu 15.04
InstallationDate: Installed on 2014-11-16 (178 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
Package: ubuntu-release-upgrader (not installed)
ProcVersionSignature: Ubuntu 3.16.0-31.41-generic 3.16.7-ckt5
Tags: vivid dist-upgrade
Uname: Linux 3.16.0-31-generic x86_64
UpgradeStatus: Upgraded to vivid on 2015-05-12 (1 days ago)
UserGroups:
_MarkForUpload: True
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