After completion of these settings, all of my applications were having a common exception either in log out or login to the web application. Here was the exception.
System.ArgumentException: Exception of type 'System.ArgumentException' was thrown. Parameter name: encodedValue at Microsoft.SharePoint.Administration.Claims.SPClaimEncodingManager.DecodeClaimFromFormsSuffix(String encodedValue) at Microsoft.SharePoint.Administration.Claims.SPClaimProviderManager.GetProviderUserKey(IClaimsIdentity claimsIdentity, String encodedIdentityClaimSuffix) at Microsoft.SharePoint.Administration.Claims.SPClaimProviderManager.GetProviderUserKey(String encodedIdentityClaimSuffix) at Microsoft.SharePoint.Utilities.SPUtility.GetFullUserKeyFromLoginName(String loginName) at Microsoft.SharePoint.ApplicationRuntime.SPHeaderManager.AddIsapiHeaders(HttpContext context, String encodedUrl, NameValueCollection headers) at Microsoft.SharePoint.ApplicationRuntime.SPRequestModule.PreRequestExecuteAppHandler(Object oSender, EventArgs ea) at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)After checking all my steps right through starting. After getting all the other exeptions cleared the above exception was the only exception that I was getting. That was resolved using "Exception of type 'System.ArgumentException' was thrown" got error when i have signout from webapplication in sharepoint 2010?.
I hope this will help to you if you are getting same error due to a silly custom property of a custom web part for registration!
Update - 5/19/2014
There are several solutions that I tried:
- Solution that is mentioned here: Exception of type 'System.ArgumentException' was thrown" got error when i have signout from webapplication in sharepoint 2010?
- In Central Administration, Application Management - select web application and in user policy, for the specific zone where you have problem (or default zone) try to remove and add all authenticated users and all fba users full read and make sure none of the AD users are showing in Domain\username format.
The same error also encountered again reported by client when he tries to enable intranet through internet explorer settings. Disabling detection of intranet from internet options solves that issue but you are forced to enter username password every first visit of the site even in intranet as well!
Update - 5/25/2014
This is a SharePoint bug also found some discussion here: https://sharepoint2013fba.codeplex.com/workitem/9
Hope this helps