do-release-upgrade
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [836 B]
Get:2 Upgrade tool [1,268 kB]
Fetched 1,269 kB in 0s (0 B/s)
authenticate 'zesty.tar.gz' against 'zesty.tar.gz.gpg'
extracting 'zesty.tar.gz'
Reading cache
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Hit http://archive.ubuntu.com/ubuntu yakkety InRelease
Get:1 http://archive.ubuntu.com/ubuntu yakkety-updates InRelease [102 kB]
Hit http://archive.canonical.com/ubuntu yakkety InRelease
Get:2 http://archive.ubuntu.com/ubuntu yakkety-backports InRelease [102 kB]
Get:3 http://archive.ubuntu.com/ubuntu yakkety-security InRelease [102 kB]
Fetched 306 kB in 0s (0 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
Updating repository information
Hit http://archive.canonical.com/ubuntu zesty InRelease
Hit http://archive.ubuntu.com/ubuntu zesty InRelease
Get:1 http://archive.ubuntu.com/ubuntu zesty-updates InRelease [89.2 kB]
Get:2 http://archive.ubuntu.com/ubuntu zesty-backports InRelease [89.2 kB]
Get:3 http://archive.ubuntu.com/ubuntu zesty-security InRelease [89.2 kB]
Fetched 268 kB in 0s (0 B/s)
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating the changes
Calculating the changes
Could not calculate the upgrade
An unresolvable problem occurred while calculating the upgrade.
This can be caused by:
* Upgrading to a pre-release version of Ubuntu
* Running the current pre-release version of Ubuntu
* Unofficial software packages not provided by Ubuntu
If none of this applies, then please report this bug using the
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done