Given the nature of the beast with enhancements, upgrades and features being marked for deprecation, it is inevitable that you will need to undertake an upgrade of your SQL Server Version at some point in time. Previously one of the first tools that you should have been reaching for was SQL Server Upgrade Advisor. Like our versions of SQL Server, the tools available to us to assist in our migrations also change. Now you should be reaching for Microsoft Data Migration Assistant (DMA) at a minimum V3.1.
So what does DMA do for us? Well it is not just limited to assisting us with upgrades between versions of SQL Server (from SQL Server 2005 -> SQL Server 2016) but also migrating to Azure SQL Database. This tool looks at assisting you in identifying any blocking issues or partial/unsupported features that may prevent you from achieving your upgrade process. From the generated report a workplan can be put together on what needs to be resolved or adjusted to achieve that migration or upgrade.
Like all tools, ensure you understand the possible impacts on your SQL Server environment prior to running this tool. If you have a lot of Instances with many databases and those databases are quite large in size with large numbers of objects that need to be checked, discretion on running the assessment needs to be undertaken to ensure you do not put any adverse impact on your system.
You can read more about the tool at the DMA blog site.