When running an older version server like 1.12.2 and wanting to upgrade to a newer version without having to make backups of your files and fear losing data, it is possible to simply one-click upgrade your existing server to a newer one with ease. This can be done within a minute.
The first step is to go to Scalacube.com and log in to your account.
Click on "Servers" and then, "Manage server".
Click "Manage" again.
Locate the "Upgrade Minecraft Version" button from the right side and click on it.
Select your desired newer version from the dropdown list and click on "Upgrade", wait for the process to fully finish.
Your server is now upgraded to your desired version.
Log into website
Go to Servers > Manage server > Manage
Click on "Upgrade Minecraft Version" and wait for process to finish