'Custom search couldn't be migrated from SharePoint 2016 to 2019

We are trying to migrate from Sharepoint 2016 to 2019 but custom search didn't get migrated properly. Custom result sources, result types, mapped properties, etc didn't get migrated. I have tried to use configuration export and import and that failed too. Does anyone know how to solve the issue? Does Microsoft stop supporting customized search in 2019 migration. Thank you.



Solution 1:[1]

Have you tried to migrate search service application from SharePoint 2016 to SharePoint 2019?

For Reference:

Search Service Migration from SharePoint 2013 to SharePoint 2016

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Casey Yang - MSFT