Unfortunately, the SQL schema upgrades happen when you update Octopus with the installer. When moving databases the versions have to be the same.
I think you would need to make a backup of your 2019 DB, then upgrade your 2019.9.10 instance to 2020.4.6, then finally attach that database to your 2020.4.6 instance.
Were you intending to keep your 2019.9.10 server on that version as a backup, or is it okay to upgrade that to get the new schema?
Optionally, you could install 2019.9.10 on the new server(instead of 2020.4.6 right off the bat), then attach the database, then do the upgrade to 2020.4.6, leaving your 2019 backup and 2019.9.10 server intact.
Yes that’s what we’re planning now .
Down the old 2019 octo server
Backup old 2019 octo database
Restore 2019 octo database to new DB
Bring up the 2019 octo server on new server
Point new 2019 octo server to new DB with 2019 data
Do in-place upgrade of octo 2019 to 2020
Pray and test.
If it doesn’t work out, down the new server and bring back up the old one