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I've hit upon yet another encodedValue error scenario:

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... bca6039c-35a7-5087-0000-057fa64c1d5b

The reproduction seems to be the following:

  1. Have a working site with Windows Authentication.
  2. Add Forms-Based
  3. Authentication with any working provider, properly configured.
  4. Test FBA. Everything works.
  5. Sign out. Everything works.
  6. When prompted after sign out, choose Windows Authentication.
  7. Everything works.
  8. Sign out.

At that point you are signed out, but you get an error. If you refresh the error page, it will work eventually (the number of refreshes needed seemed to be steady at two, but that proved false).

The FBA sign in before Windows is not necessary, it is just here to allow demonstrating that the FBA provider is working and not causing the issue (seemingly).


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up vote 3 down vote accepted

I called Microsoft on this (case 11303​0110256288) and it's a product bug in 2013 - apparently a regression from 2010. Another customer had reported the same issue. It's an acknowledged bug with no KB yet. They hope to pick it up in an upcoming cumulative update but it wasn't know when to expect it yet.

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