Could not load type 'System.Web.Security.Formsauthenticationmodule'


  • I facing this error after upgrade my Visual Studio to 2015. I search on internet for solution but didn't find any topic related.

    Plese give me some idea to solve this. Thank you.

    It's urgent....

    Saturday, December 26, 2015 10:26 AM


  • Hi Lee C.C,

    What’s your project type?  Where does this error occurred? in building or in debugging or in some other situations ?

    And was your project created in old version VS? 

    Could you provide some more detailed information about your issue.

    I did a research for the error message you offered.

    And I found “System.Web.Security FormsAuthenticationModule” is a class which is in System.Web.Security namespace and is related to your .net framework.

    You could refer to the following link about System.Web.Security Namespace.

    So try to change your .net framework to the old version then try it again.(Make sure the version of .net framework in VS2015 is same with the project created version)

    For example: if the project created in VS2010 and the .net framework version is 4.0. In VS2015, change the .net framework to 4.0 and try it again.

    If above suggestions still have no help. I suggest you’d better provide us detailed log information so that we could troubleshoot the issue.

    Best Regards,

    Lake Xiao

    Monday, December 28, 2015 7:32 AM