For data migration, you can use RapidStart Services (configuration packages), export data from the original system in Excel files, and import them into Microsoft Dynamics 365 Business Central on-premise and SaaS.
The biggest problem is obviously rewriting code with the new extension model (which is mandatory if you want to go to the cloud, but not mandatory for Microsoft Dynamics 365 Business Central on-premise).
You can use these tools for data migration:
- RapidStart packages (configuration packages)
- Intelligent cloud (you can replicate data from on-premise to SaaS)
- APIs (you can use APIs to upload data)
- Data migration extension (not available to date, but is in development by Microsoft, and is already available for other products)
