After deleting a database with a modern public folder with adsiedit, the IT administrators was called by one of his coworkers company that the Public Folder, with the complain that his public folder was empty. While in the morning the folder did contain a lot of messages he was working with.
After inspecting the question it was clear the a previous migration of the modern public folders had failed. And that the messages of that Public Folder where not synchronized to the other Public Folder.
The Database with the Public Folder still existed on one of the Exchange servers.
The Database and log folders where copied to another Exchange Server
With some 3rd party tooling is was clear that the databases contained the missing Public Folder. Only the tooling need to be bought when restoring data from the database. The database was mounted with Powershell: Then a Backup was made with Veaam. When it was finished, Veaam Explorer was lounged to investigate
Mount-Database <database> –Force
Then a Backup was made with Veaam. When it was finished, Veaam Explorer was lounged to investigate the backup.
With the Backup, the Public Folder in the datase, could be exported to a .pst file. Which could in succession be restored into the empty Public Folder in the Exchange oranisation.