Sitefinity 13.3 and support for Web Forms: What You Need to Know

Scott Snowden
Scott Snowden
Business & Technology Strategy
Write to Scott

Sitefinity 13.3 is about to be sunset, and this is important news for many customers. This version is the last one that officially provided support for ASP.NET Web Forms, a legacy Microsoft technology used for building templates and widgets in Sitefinity. While Web Forms technology was widely used in the past, newer technologies such as MVC or ASP.NET Core are more secure, faster, and provide a better overall user experience.

In the following video and in the remainder of this article we explain what this means in more detail:


Sitefinity has a comprehensive life cycle policy, which is explained in detail on their support site. When a product is retired, support is only provided on a best-effort basis. Before retirement, there is a period called Sunset, during which technical support is still provided, but no enhancements are made to the product. Critical patches and updates are at the discretion of Sitefinity.

According to the life cycle policy, Sitefinity 13.3 LTS will reach Sunset in March 2024. If you are using a version prior to 13.3, it is important to upgrade to at least this version. However, it is also important to start planning for the future and considering newer web technologies. We recommend moving to ASP.NET Core.

While the operation of your Sitefinity website will not be affected when the retirement date arrives, it will no longer be supported by Sitefinity. It is important to start planning for a gradual migration to avoid business disruption and undue urgency of needing to migrate later. There are strategies and approaches that can make this process manageable and ensure that your site is up to date and secure before critical dates pass.

Frequently Asked Questions

We get some common questions from clients who are contending with this lifecycle timeline:

Q: Can you just “upgrade” my site and switch from Web Forms to .NET Core?

A: We think of this more as a migration than an upgrade. So, no – you cannot just upgrade your site as is. The existing code and components cannot be upgraded in place. New templates and widgets need to be built to replace anything that uses Web Forms. In this process you may decide to stop using some components and add new ones. There are also new features of Sitefinity that you can take advantage of to optimize how your site is built.

Q: How much will it cost to switch from using Web Forms to .NET Core?

A: That depends. There are two parts of this endeavour that need to be considered. First, there is a code change that will be necessary to replace your templates and widgets and other functional components. Then, you need to work through a content exercise to recreate your pages to use those new components. So, the cost ultimately depends on how many templates and widgets you use AND how many pages exist on your site. Often, we’ll conduct an initial audit to establish a more formal cost estimate for the migration project.

Q: How long does a migration project take? Can it be done in a phased approach?

A: Similar to the cost question, the timeline for a migration will also depend on the site of your site, available resources to assist with content management and the budget available. It is possible to plan a migration in a phased manner as the legacy technology and the current technologies can be run side-by-side.

Q: What happens to my site after Web Forms is no longer supported? Will I get hacked or have security, privacy issues?

A: Your site will continue to function after the support date passes. However, if there is an issue (i.e. bug, vulnerability) discovered, it will not be possible to get support to fix that issue. In that case you may be forced to upgrade and migrate urgently, or find another workaround. The simple lapse of the support date does not immediately increase the risk of having a privacy, security or other performance issue, but your capability to address any potential issues will be compromised.

Q: What are the other options if we do not want to migrate or don’t have the budget right now?

A: There are essentially 4 options to consider if you need to migrate away from Web Forms:

  1. Complete a formal migration to a modern technology and a recent version of Sitefinity.
  2. Defer the decision for now. You could assess your risk and do nothing if you feel it is appropriate. Your site will continue to operate and that may be ok for your business and risk profile.
  3. Phase in your migration by doing certain, higher profile sections of your website as soon as possible. Address the rest of your site later. The legacy Web Forms technologies and the more modern frameworks (i.e. ASP.NET Core) can run side-by-side.
  4. Consider an alternative platform. You may be better served by adopting a different infrastructure altogether or merging several sites together.

Get in Touch

At Flywheel, we are working through several projects of this nature, and we can help you determine the best path forward for your organization. We’re happy to discuss your circumstances and provide our advice on this matter for free.

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