You shouldn't need to run update-manager with sudo, it will elevate privileges later on during the process. Additionally, it looks like it was attempting to upgrade to 15.10 (wily). Is that the release you want to upgrade to? If not then edit /etc/update-manager/release-upgrades and change Prompt to lts instead of normal.
You shouldn't need to run update-manager with sudo, it will elevate privileges later on during the process. Additionally, it looks like it was attempting to upgrade to 15.10 (wily). Is that the release you want to upgrade to? If not then edit /etc/update- manager/ release- upgrades and change Prompt to lts instead of normal.