I am attempting to upgrade from mojoPortal 2.3.1.6. Currently, I am trying to get 2.3.3.6 to work, but I got an identical error when I attempted to upgrade to 2.3.1.7. (I did a clean restore to 2.3.1.6 between upgrade attempts.) The installation appears to run successfully,but when I try to log into any site after the upgrade, I get the following error message in my browser (happens in both FF & IE):

Server Error in '/' Application.
Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific

error details below and modify your configuration file appropriately.

Parser Error Message: Exception has been thrown by the target of an invocation.

Source Error:

[No relevant source lines]

Source File: Line: 0

Version Information: Microsoft .NET Framework Version:2.0.50727.3603; ASP.NET Version:2.0.50727.3082

The log file shows the following errors:

2010-02-17 11:05:16,957 ERROR mojoPortal.Web.mojoBasePage - 127.0.0.1-en-US - /Secure/Login.aspx
System.TypeInitializationException: The type initializer for

'mojoPortal.Business.WebHelpers.UserSignInHandlers.UserSignInHandlerProviderManager' threw an exception. --->

System.Configuration.ConfigurationErrorsException: Exception has been thrown by the target of an invocation.
at System.Web.Configuration.ProvidersHelper.InstantiateProvider(ProviderSettings providerSettings, Type providerType)
at System.Web.Configuration.ProvidersHelper.InstantiateProviders(ProviderSettingsCollection configProviders, ProviderCollection

providers, Type providerType)
at mojoPortal.Business.WebHelpers.UserSignInHandlers.UserSignInHandlerProviderManager.Initialize()
at mojoPortal.Business.WebHelpers.UserSignInHandlers.UserSignInHandlerProviderManager..cctor()
--- End of inner exception stack trace ---
at mojoPortal.Business.WebHelpers.UserSignInHandlers.UserSignInHandlerProviderManager.get_Providers()
at mojoPortal.Web.UI.SiteLogin.OnUserSignIn(UserSignInEventArgs e)
at mojoPortal.Web.UI.SiteLogin.SiteLogin_LoggedIn(Object sender, EventArgs e)
at System.Web.UI.WebControls.Login.OnLoggedIn(EventArgs e)
at System.Web.UI.WebControls.Login.AttemptLogin()
at System.Web.UI.WebControls.Login.OnBubbleEvent(Object source, EventArgs e)
at System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args)
at System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e)
at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)
at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
2010-02-17 11:05:17,057 ERROR mojoPortal.Web.Global - 127.0.0.1-en-US - /Secure/Login.aspx
System.Configuration.ConfigurationErrorsException: Exception has been thrown by the target of an invocation.
at System.Web.Configuration.ProvidersHelper.InstantiateProvider(ProviderSettings providerSettings, Type providerType)
at System.Web.Configuration.ProvidersHelper.InstantiateProviders(ProviderSettingsCollection configProviders, ProviderCollection

providers, Type providerType)
at mojoPortal.Business.WebHelpers.UserSignInHandlers.UserSignInHandlerProviderManager.Initialize()
at mojoPortal.Business.WebHelpers.UserSignInHandlers.UserSignInHandlerProviderManager..cctor()

This is on a system running Windows 2003, IIS 6, MSSQL, with the latest updates and service packs (including .NET 3.5 SP 1). If I am logged into the primary site when I run the upgrade, I remain logged in. However, I cannot log into any other sites running off the same database,and if I log out of the primary site, I cannot log back in. The database records show the most recent login at approximately the sametimestamp as the error in the config file.

This error is occurring on the virtual machine I use for testing, so no customer sites are affected by this. Simply viewing sites (while notlogged into the site) works fine. If I restore my previous database and files, the login feature works properly again.

Any ideas why this would be happening?

Yes, /Setup/ProviderConfig/usersigninghandlers/000_placeholder.config does exist. 

There is another file in this folder, 1000_mycustomsigninhandler.config, which I use to handle some custom sign in logic.  This is done in a custom project I created following your instructions on User Sign In Handlers.  This custom handler has worked fine in previous installations. 

Will I need to rebuild my project to work with the latest version of the core code?

Lorien