I am also getting a request validation error when using WIF. I get correctly sent to the STS, but on the way back, I get this validation error.

I followed all the instructions. 

```
<httpRuntime  requestValidationMode="2.0" />

```

check!

```
    [ValidateInput(false)]

```

check!

```
<pages validateRequest="false" >

```

check!

I tried a custom validator, but it never gets instantiated. 

Error stack:

```
[HttpRequestValidationException (0x80004005): A potentially dangerous Request.Form value was detected from the client (wresult="trust:RequestSecuri...").]
   System.Web.HttpRequest.ValidateString(String value, String collectionKey, RequestValidationSource requestCollection) +11396740
   System.Web.HttpRequest.ValidateNameValueCollection(NameValueCollection nvc, RequestValidationSource requestCollection) +82
   System.Web.HttpRequest.get_Form() +212
   Microsoft.IdentityModel.Web.WSFederationAuthenticationModule.IsSignInResponse(HttpRequest request) +26
   Microsoft.IdentityModel.Web.WSFederationAuthenticationModule.CanReadSignInResponse(HttpRequest request, Boolean onPage) +145
   Microsoft.IdentityModel.Web.WSFederationAuthenticationModule.OnAuthenticateRequest(Object sender, EventArgs args) +108
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +270

```

Any suggestions?