Please report this as a bug (if you haven't already) and include the files /var/log/dist-upgrade/main.log and /var/log/dist-upgrade/apt.log in your report. The upgrade has aborted. Your original sources.list was saved in /etc/apt/sources.list.distUpgrade.
Adrodda hwn fel chwilen (os nad wyt ti eisoes wedi gwneud) gan gynnwys ffeiliau /var/log/dist-upgrade/main.log a /var/log/dist-upgrade/apt.log yn dy adroddiad. Mae'r uwchraddiad wedi terfynu. Cadwyd dy sources.list gwreiddiol yn /etc/apt/sources.list.distUpgrade.