Understand why SAP Business One shares a vendor with ECC and S/4HANA but not an architecture, and why the first honest question in the programme is whether D365 F&O — rather than Business Central — is the right target at all.
The most expensive sentence in a SAP Business One migration is spoken in the first week, usually by someone senior and usually with confidence: "we've done SAP before."
Most migration paths on this site begin by assuming the target. This one does not, because the source material is unusually direct about it: the most important Business One migration question is often not how do we map this to D365 F&O but should this estate move to Business Central instead.
A company database is the primary boundary. Each company runs in its own database, on either SQL Server or SAP HANA. Configuration, master data and transactions live inside that boundary.
Almost everything a design can say about a Business One estate is conditional on facts that vary between installations. The adapter treats a specific list as required discovery input, and the playbook repeats it as a mandatory fingerprint. Capture it before scope, effort or cutover approach are committed:
A handful of version facts materially change what an integration or extraction design can assume.
The conceptual model page reduces the danger to five statements. They are worth committing to memory, because each one has burned a programme.
Two shifts dominate the finance workstream and are worth previewing here so the vocabulary lands early.
The adapter is explicit about the confidence boundary, and repeating it is more useful than pretending to certainty.
SAP Business One and D365 F&O both produce audit-defensible, period-closed accounting. They arrive there from opposite ends of the market, and the migration is the work of re-projecting one set of design choices onto another.