Migrating a Classic ASP Application to ASP.NET Core

A Classic ASP application is migrated to ASP.NET Core by rebuilding it, page by page or module by module, while the old site stays live. The business logic in the ASP pages is separated from the screen code and rewritten in C#, the database is kept or upgraded, and sections go live as they are finished. There is no automatic converter that does this well, because Classic ASP and ASP.NET Core are built on different ideas.

Signs this is your problem

• Your pages end in .asp, not .aspx.
• A server upgrade or hosting move is being held up by the application.
• A security scan or a customer questionnaire flagged the site.
• Small changes take a long time because nobody wants to touch the code.
• The site does not work properly on phones.
• The original developer is gone.

Why Classic ASP is on borrowed time

• It stopped evolving a generation ago. The last version, ASP 3.0, arrived with Windows 2000. Microsoft still lets it run on its web server, but nothing has been added since.
• Its language is being retired. Most Classic ASP is written in VBScript, and Microsoft has announced that VBScript is being phased out of Windows.
• Old code carries old security habits. Much Classic ASP was written before today’s attacks were common, and builds database commands in ways that are now known to be dangerous.
• It leans on components nobody maintains. Email, file upload and PDF parts from that era are often unsupported.
• Finding people is getting harder. Few developers today have ever worked in it.

The application may run for years yet. The question is whether you move on your schedule or on the day something breaks.

What a migration actually involves

In Classic ASP, the screen layout, the business rules and the database commands are usually mixed together in the same file. A good migration separates them:

• Business rules are pulled out and rewritten in C#, where they can be tested.
• Database access is rewritten safely, and the database is moved to a current version of SQL Server if needed.
• Screens are rebuilt to work on phones and modern browsers.
• Logins and permissions are replaced with current, secure methods.

Large applications are moved in sections. Old and new run side by side behind the same address, so users see one site that steadily gets better.

You keep what makes the system yours

The value in a Classic ASP application is rarely the code. It is the years of business decisions the code represents. We treat the existing application as the specification, confirm each rule with the people who use it, and carry it forward. Your data comes with you.

How Keene Systems handles it

1. We review the code and the database. You get a clear picture of size, risk and a sensible order of work.
2. We agree what moves first. Usually the parts that carry the most risk or get the most use.
3. We rebuild in ASP.NET Core, section by section. Each section goes live when it is ready.
4. We retire the last of the old code. And the old server with it.

The next step is a short, no-pressure conversation. Book a call with Lance Keene or use the form on this page.