How can I DownGrade from version 10 to version 9
Downgrading is not supported in the Outsystems Platform.
Download / Backup the latest OS 9 versions of your applications / eSpaces using a solution.
Delete the platform from the server and reinstall version 9.
Install the applications / solution to the new environment.
Version 9 and 10 can exist next to each other, no need to uninstall version 10 (version 9 should still be installed on your environment).
Ask Outsystems Support if they can downgrade your environment (make sure you have the backup of the last OS9 versions of your applications.)
It is not possible to downgrade. Open the eSpace / Extension and copy/paste or recreate based on the info you have in OS 10 version.
I hope you can work with these options, otherwise I would like to know what else you want to downgrade,
Can you share why do you want to downgrade from 10 to 9?
Many moons ago I worked in a downgrade from, IIRC, 4.0 to 3.3.
It was not an easy thing to do.
And it was only possible because we had the good idea of making a backup of the OutSystems database before the upgrade.
In theory, if you have a backup of the OutSystems database you should be able to "downgrade" to 9.0, but in practice you'll likely run into all sorts of issues.
Oh, and any new developments made with P10 will be lost.
We've been receiving quite a few of these questions regarding Personal Environments so I suspect this may be the case.
Just to clarify, it's not possible to downgrade Personal Environments or create new ones in versions prior to OutSystems 10.