The standard measure of a successful migration: does the new system produce the same results?

The standard measure of a successful migration: does the new system produce the same results?

The answer is almost always: “yes — for the transactions we tested.”
PowerBuilder applications accumulate edge cases over decades. A pricing condition for a contract signed in 2004. A regulatory format that applies only to one account type in one jurisdiction. A validation rule adjusted after an incident in 2011 by a developer who left three months later.

These cases are not in the test suite.
They surface when a financial auditor, a regulator, or a major client encounters them — in production.

A migration that processes 99.9% of transactions identically is not successful in any system where the remaining 0.1% touches money, compliance, or contractual obligations.

The 0.1% is not a rounding error.
It is the thing your organization will be held accountable for.

You can find relevant information in the specific section: https://enable-dev.com/modernization

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