Microsoft has not put an end date on Web Forms. It also does not exist on ASP.NET Core. We will tell you whether to keep it on supported Windows, or start leaving it, without a rebuild from scratch.
Australian .NET team. We look at the app before anyone talks about a rebuild.
01
What you have
02
What is safe to keep
03
Upgrade or move
The app still works. That is why it has been left alone.
Most of the Web Forms systems we hear about were built when .aspx and the designer were the default. Then the person who understood the postbacks left, and the control suite became the product.
You might recognise one of these:
You do not need a new brand, or a product pitch. You need a clear read on the application you already have.
Web Forms is still a documented Microsoft framework. It ships inside .NET Framework. Support follows the Windows version under it. The problem is rarely “Web Forms died on a calendar date”. It is the gap between the app you have and a stack you can still hire for, host, and change.
Microsoft’s own guidance is blunt: ASP.NET Web Forms are only available in .NET Framework. ASP.NET Core cannot run them. Server controls, the page lifecycle, postbacks, and ViewState have no 1:1 destination. Microsoft’s migration docs start a new Core project and proxy to the old app. Pages are rewritten, not retargeted.
Telerik, ComponentArt, Ajax Control Toolkit, and the rest of that era’s .aspx suites have no Core equivalent. If the screens are those controls, a csproj change will not save them.
Framework 4.8 and 4.8.1 are still supported, as a Windows component, for as long as the host OS is supported. There is no standalone Web Forms end-of-life date. What does end: Windows Server 2012 and 2012 R2 extended security updates, in mid-October 2026; Windows Server 2016 extended support, in mid-January 2027. Older Framework runtimes (4.5.2, 4.6, 4.6.1) already ended on 26 April 2022. The app does not switch off when those dates pass. The box under it stops being a supported place to run it.
Framework 4.8 gets OS-tied security servicing. Web Forms is not receiving new framework investment. Security of your pages still depends on IIS, the libraries you bolted on, and the custom code from 2012. A Framework patch does not fix an old Forms Auth setup or a TLS endpoint you wrote yourselves.
HttpContext, Forms Authentication, and session are different APIs on Core. Microsoft documents System.Web adapters and remote session / remote authentication as a bridge, not as the finish line.
None of that makes the business rules or the data worthless. It does mean “the app will die in 2026” is the wrong first sentence, and “flip a compiler flag” is the wrong first move.
We start with the app, not with a destination.
Framework version, page count, third-party controls, session and auth, how much of the logic lives in code-behind versus class libraries, and the Windows Server under it. We will tell you what can stay, and what has no path onto modern .NET.
There are three honest outcomes. We recommend one, not all three.
If you are leaving, we follow the path Microsoft documents: a new ASP.NET Core front, a reverse proxy, adapters where they help, and a rewrite of routes that actually get used. Unused screens do not come across.
Source, a short record of what changed, and an app someone else can understand.
We will not tell you Microsoft deprecated Web Forms. We will not tell you WordPress is the answer to a line-of-business app. If you already know you want to stay on Web Forms forever, that can be a responsible choice on a current Windows Server. If you want an honest fork in the road, talk to us.
A URL or a screenshot of the app, and a rough Framework version, is enough to start.
The first call is 30 minutes. You leave with a recommendation you can take to a manager, not a rewrite estimate pulled from thin air.
We have taken over and modernised ageing .NET systems for Australian organisations, including work with Data#3, Hastie, NESS, and NSW Health. Hastie was a SharePoint 2007 plus ASP.NET 3.5 portal. NSW Health TESL replaced a ColdFusion / Classic ASP leave system with SharePoint and ASP.NET 4.0. That is related Microsoft web work, not a published Web Forms-to-.NET 10 case study. Your app still starts with its own assessment. We will not pretend it is a project we have already published.
Thirty minutes. Bring a URL and a Framework version if you know it. We will tell you whether to keep it on supported Windows, start leaving Web Forms, or leave it alone for now.
Book a free 30-minute discovery call