I migrated SharePoint from 2013 to 2016 and then 2019. I used the database prefix SP_Intranet.
After migration to 2016, I removed SP_Intranet_Config and SP_Intranet_CentralAdmin + non-migrable databases.
This was followed by the installation of SharePoint 2019 with the latest patches. The farm consisted of four servers, the migration was successful. SharePoint server 2016 was still running but without databases. After two days in "Review problems and solutions" I got an error message: Product / patch installation or server upgrade required. .. Can you please tell me how to fix this error message?
In my opinion, since SharePoint server 2016 contained a database with the same name and continued to run, it joined the databases that were already created for SharePoint 2019.
Run the Get-SpProduct -Local after that run the Config wizard. I would use this psconfig -cmd upgrade -inplace b2b -force
Clear the Config Cache on All server in Farm then run the psconfig wizard.
Sharepoint 2016 was installed on other servers. However, the database server is the same.