When migrating to managed instance from SQL Server, most features are supported, but you need to assess your SQL Server and the databases you want to migrate to ensure there aren’t any features enabled that aren’t supported.
You can do this with the Data Migration Assistant (DMA). Unlike migrating to Azure SQL Database, you won’t be able to migrate to managed instance with DMA, but it’s an excellent way to assess any issues you may need to fix before the move to managed instance.
Download the DMA here:
https://www.microsoft.com/en-us/download/details.aspx?id=53595
After installing the DMA, open it and click the + to create a new project
Choose project type Assessment, name your project, choose Source server type SQL Server and Target server type Azure SQL Database Managed Instance
On the options screen, leave Check database compatibility and check feature parity checked and click Next
Enter the name of your SQL Server in the Server name field and choose the authentication type. I’m using Windows Authentication since my Windows user has sysadmin perms. Click Connect.
Choose the database you want to assess and click Add.
Click Start Assessment.
Here’s where you can review the results of the SQL Server feature parity with recommendations of how to remediate and issues.
Click the Compatibility issues radio button to see any database issues
You can choose to Upload to Azure Migrate (this uploads the results) if you have an Azure Migrate project setup.
https://docs.microsoft.com/en-us/sql/dma/dma-assess-sql-data-estate-to-sqldb?view=sql-server-2017
Then your results will be in the Azure portal.