Every time something like this has been done on my company I follow up with the question: did anyone watched the code to see if the business logic is the same between the two versions?
The answer is: but but but automated testing.
Followup question: did anyone read the automated test suite?
Silence.
The software rewrite is shelved.
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Honest question: does that even remotely matter, or is it an outdated prior? All software has bugs.
The goal and objective is to deliver value for your user/customers; to the speed, reliability, and assurance requirements your market segment expects.
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