Ubuntu Vivid end of life is this month, and Utopic is not even listed on their releases at this point.
Anyone using dCore-utopic is advised to move to another dCore release. dCore-utopic installs will still have their DEBINX available and can still be used, but the release and release candidates are gonig to be removed and no longer updated. Also, those filing bug reports involving dCore-utopic will be asked to first migrate to another release.
Those using dCore-vivid are advised to move to another dCore by the end of the month.