Hi,
Sorry he double slash in the path is a copy/past error !
Yes it’s weird, error is clear but not verbose and I can’t rollback to release 3.16.1
I’m cursed with updates 
ghost update --rollback
+ sudo systemctl is-active ghost_mydomaincom
✔ Checking system Node.js version
✔ Ensuring user is not logged in as ghost user
✔ Checking if logged in user is directory owner
✔ Checking current folder permissions
✔ Checking folder permissions
✔ Checking file permissions
✔ Checking content folder ownership
✔ Checking memory availability
✔ Checking for available migrations
✔ Checking for latest Ghost version
ℹ Downloading and updating Ghost [skipped]
+ sudo /srv/mydomaincom/current/node_modules/.bin/knex-migrator-rollback --force --v 3.18.0 --mgpath /srv/mydomaincom/current
✖ Rolling back database migrations
A ProcessError occurred.
Message: The database migration in Ghost encountered an error.
Help: https://ghost.org/faq/upgrade-to-ghost-2-0/#what-to-do-when-an-upgrade-fails
Suggestion: ghost update --rollback
Debug
Debug Information:
OS: Ubuntu, v18.04.4 LTS
Node Version: v12.17.0
Ghost Version: 3.18.1
Ghost-CLI Version: 1.14.0
Environment: production
Command: 'ghost update --rollback'
Message: The database migration in Ghost encountered an error.
Help: https://ghost.org/faq/upgrade-to-ghost-2-0/#what-to-do-when-an-upgrade-fails
Suggestion: ghost update --rollback
--------------- stderr ---------------
[2020-06-02 19:07:32] ERROR SQLITE_CANTOPEN: unable to open database file
ghost doctor
✔ Checking system Node.js version
✔ Checking logged in user
✔ Ensuring user is not logged in as ghost user
✔ Checking if logged in user is directory owner
✔ Checking current folder permissions
✔ Checking operating system compatibility
+ sudo systemctl is-active ghost_mydomain-com
? Sudo Password [hidden]
✔ Validating config
✔ Checking folder permissions
✔ Checking file permissions
✔ Checking content folder ownership
✔ Checking memory availability
✔ Checking binary dependencies