IIS still ships the Classic ASP runtime, so a twenty-five-year-old VBScript application keeps limping along with no debugger, no tests, no dependency management, and a security surface from another century. Because it never quite dies, it never gets budget, until the one person who understood it leaves.
I migrated a music-rights royalty system and a twenty-year Billboard chart archive off Classic ASP, the second one to Blazor on Azure, with the business publishing throughout. Same pattern every time: get the database somewhere safe first, put the new application beside the old one, and switch pages over one at a time. Where the old code has no documentation, an LLM-assisted pass with a confidence score on every record finds what the code actually does faster than reading it line by line.
Your Silverlight app has no browser to run in. The code still says what it does.
LightSwitch generated your app. You cannot regenerate it, but you can read it.
Delphi is alive. Your Delphi 5 codebase, on components that no longer compile, is not.
Your records are in Notes databases. Someone has to read the Notes data model to get them out.