Pretty tame compared to some stories out there, but I recently worked for a company that had the most amazing process for importing customer data when customers

Pretty tame compared to some stories out there, but I recently worked for a company that had the most amazing process for importing customer data when customers migrated to our SaaS from a competitor. First the data dump provided by the customer is run through a VB6 conversion program that imports the data to an Access97 database. Then the Access db gets opened using a legacy VB6 version of our product from roughly the year 2000 where they verify that everything was converted and imported correctly. Then they run the Access database through a second VB6 conversion program to migrate it into SQL Server so it could be used with the current SaaS product. The source for the legacy product was at least in source control, but only one engineer still working for the company had ever touched that application at all. From what I was told the source for both of the conversion programs was lost years before I joined. The company's ability to import data for new customers was 100% dependent on this rickety pipeline.