I do not know what is the exact issue here. But probably you can rollback the changes to get your site back online.
Then install a local copy of a site backup and try to upgrade the Ghost to the latest version on that before you do it on the live server.
Rollback command
ghost update --rollback
or consider a force update (I do not recommend)
ghost update --force
Docs: Ghost-CLI - A fully loaded tool for installation and configuration
BTW, I came here to check if someone’s having issues after updating the ghost to 2.8.0. Before performing the update command on my server.
