Ubuntu – skip over releases when upgrading

Ubuntu only supports upgrading from one version to the next version, or from one LTS version to the next LTS version. So you need to upgrade from 10.04 to 10.10, and only then to 11.04.

There are technical reasons for this restriction. When a new version of an existing package is installed it sometimes has to perform conversions, e.g., it may have to import existing settings into a new database format. In performing such conversions the packaging scripts have to make assumptions about the old format. If upgrades from all previous versions of Ubuntu were supported then this would quickly become a maintenance nightmare, as packaging scripts would have to be able to convert from all previously used formats to the current format. To avoid the nightmare, packaging scripts only in general support upgrading from the version of the package included in the previous Ubuntu release (and from the previous LTS release, in the case of a package included in an LTS release).

Upgrading directly from the penultimate, or earlier, version to the current version (called a "skip upgrade) is possible, but is liable to result in a misconfigured system.