Then there are the Rube Goldberg internal systems made up of an obsolete version of Lotus Notes trying (and failing) to interact with an obsolete version of Microsoft Office, backed by excel spreadsheets that automatically corrupt any data entered into them, tied to Access databases with a custom Visual Basic front-end that wouldn’t run on any computer from the last 18 years.
One case there were 3 separate datasources, all old Cobol systems, which would have been ok, but none of them agreed with what was in the Excel sheets, which weren’t even formatted right.
Then there was the company that still used old DOS programs for everything but wanted a modern web interface. Some of the stuff couldn’t even be converted to a modern format without manual re-entry because it was in a weird proprietary format.
It’s been a few years, but not that long, when I was just listening in on a phone call and the client was concerned about whether things would still work with IE 6, because that was what all the executives used, and the agency guy said “Not a problem, just send us an address and we’ll send them all new laptops. It’ll be cheaper and less hassle for all of us.” On mute, I laughed my ass off.