Migration from SBS 2008 to Windows Essentials 2019

Hi Martin,

It should be possible.
Please make sure to refer official migration guide first.
https://docs.microsoft.com/en-us/windows-server-essentials/migrate/migrate-windows-small-business-server-2011-essentials-to-windows-server-essentials 

following post may be helpful,
https://windowsserveressentials.com/2017/03/28/migrate-sbs-2011-standard-to-windows-server-2016/ 

Thanks, but this is SBS 2011 to Windows Essentials 2016

Same steps basically for all SBS version. Please note the 21-day grace period. KNOW BEFOREHAND you can fully transfer WITHIN this period.

You can't do what you want.

The version difference is too great so you won't successfully promote the 2019 server as a DC.

And even if you use other methods (such as an interim server) to make the move, you cannot demote a domain controller that has exchange on it without breaking exchange. Which was your second question.

You will want to be on O365 before making any other moves.  Or plan on moving to a other version of exchange.  No matter what, moving your mail will have to happen before moving your domain controller. 

I built a test scenario on Vmware
Well, promoting the 2019 Essential was a little bit tricky, but it worked.
1. As stated I installed all available updates for the SBS.
2. I raised the functional levels https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/active-directory-functional-levels on the SBS to 2008
3. I had to migrate to DFRS on the SBS
Afterwards the 2019 server joined the SBS domain.
You are quite right regarding Exchange. Though all the service seem to work, I´ll better export the users to PSTs and try to move to O365.first.

Well, I did it. Build up Office 365 with Exchange. Exported the mails via PST, uninstalled Exchange 2007 and imported the PSTs into Exchange online.
Afterwards I put the Essentials 2019 into the domain and promoted it afterward to DC. It now has all the roles.
After migrating a few software packages the 2008 is going to be retired.