The Server extension will preserve certain values. Below you will find a complete list of values that require the Server extension. The server extension is not compatible with SharePoint 2003
Note: You do not need the server extension in Microsoft 365, but you could still need it on your source or destination if it is on-premises. It's not only recommended to preserve these values, but it can also increase the performance during the migration.
Value to preserve
Install the Server extension on
|Authors and timestamps||all versions||2007||Destination|
|Modified by on Draft Versions||all versions||2010, 2013, 2016, 2019||Destination|
|Approval status (with authors and timestamps)||all versions||all versions||Destination|
|Business data (BDC)||all versions||2007||Destination|
|Content type OOB (Out-Of-the-Box) workflow configuration||2007||all versions||Source|
|Items declared as Records||2010, 2013, 2016, 2019, M365||2010, 2013, 2016, 2019||Destination|
|Items with a high version number on the first version||all versions||all versions||Destination|
|List OOB (Out-Of-the-Box) workflow||2007 Foundation (WSS 3.0)||all versions||Source|
|Nintex workflow constants||all versions||2010, 2013, 2016, 2019||Source and Destination|
|Nintex workflow history||all versions||all versions||Source and Destination|
|User alerts||2007, 2010, 2013, 2016, 2019||2007, 2010, 2013, 2016, 2019||Source and Destination|
For example, using the above table, you can see that if you wish to preserve the value Authors (Modified by) on Draft Versions, the Source (i.e. starting point of your migration) can be any version of SharePoint, but if the Destination (i.e. where you are migrating to) is either SharePoint 2010, 2013, 2016, you need a Server extension that must be installed on the Destination version of SharePoint.