trying to upgrade from ubuntu 12.04 to 12.10
enter update-manager -d in the terminal and everything goes fine until i get this error message
An unresolvable problem occurred while calculating the upgrade:
E:Unable to correct problems, you have held broken packages.
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.
the upgrade then stops and my system reverts back to 12.04