I'm trying to install WFFM into Sitecore XP 8.1.

Following installation, the WFFM options appear in the desktop as expected. However, if I then do a clean and rebuild in Visual Studio, I then get the following error whenever I try to access any page on the site/in sitecore:

Could not resolve type name: Sitecore.Form.Core.Utility.HttpContextPerRequestStorage, Sitecore.Forms.Core (method: Sitecore.Configuration.Factory.CreateFromTypeName(XmlNode configNode, String[] parameters, Boolean assert)).

I then have to roll back all changes in order to bring the site back up - when I do this, the WFFM option is still present in my desktop menus, but then disappears again when I sync with Unicorn.

Can anyone enlighten me on this? I'm very new to Sitecore (picking up a project from someone else), and there seems to be no documentation for if things go wrong like this...


2 Answers 2


When you directly set up your IIS site to use your folder where the Visual Studio solution placed it can happen because of the Rebuild. Rebuild means cleaining up your bin folder and only take the assemblies which are in your Visual Studio project.

So if the Sitecore.Form.Core.dll is not used in your project then the Rebuild removes it. If you setup the site like this then you should only Build.

I suggest to you to setup a different root folder for your IIS and do a publish from Visual Studio to the clean Sitecore instance.

Here is a good article how to setup Sitecore with Visual Studio project - https://doc.sitecore.net/sitecore_experience_platform/developing/developing_with_sitecore/set_up_sitecore_and_visual_studio_for_development.


Turns out that I had been given the wrong version of WFFM for the version of Sitecore I was working with - annoyingly I am currently blocked from downloading packages myself, and it was only thanks to another developer that this was spotted.

So apologies for such a basic error - and thanks to Tamas for the article link, very handy for a beginner like myself.

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