I tried to update from 13.04 to 13.10. Got the "Could not calculate the upgrade" error
51768
Could not calculate the upgrade, what happened?
30754
Cannot update: "No available releases found"
40001
Mac App Store update stuck (Installing - Calculating...)
110148
Why does `do-release-upgrade` skip a version?
94171
Why Does Software Updater Say No updates Available, but apt-get upgrade Shows updates available?
86777
Distribution upgrade problem "No new release found"
50810
No upgrade available for 19.04 from 18.10
35146
Will apt-get dist-upgrade upgrade my system to newer version?
24165
Upgrade to version newer than repositories
126659
upgrade from 11.10 to 12.04 - No upgrade option available in update manager
67481
How to revert a do-release-upgrade?
13970
Why am I not getting the Ubuntu 18.04 upgrade?
33651
How to upgrade from Ubuntu 12.10 to 14.04
1520
How to install software or upgrade from an old unsupported release?
19288
Update manager doesn't offer an upgrade to the new release
77705
Unable to upgrade in ubuntu
112955
How can I upgrade Ubuntu from 19.10 to 20.04 without losing packages?