Error en 1.19.1.7 en pantalla Administración de Usuarios

Buen Dia, comentarles que tengo un error en la versión 1.19.1.7 en pantalla Administración de Usuarios cuando el parametro UsernameEsModificableEnPantallaUsuarios está en True. El error se muestra al dar clic en guardar.

System.Data.ConstraintException This property cannot be set to a null value.

System.Data.ConstraintException: This property cannot be set to a null value. at System.Data.Entity.Core.EntityUtil.ThrowPropertyIsNotNullable(String propertyName) at Aseinfo.Infrastructure.Data.Usuario.set_Username(String value) in C:vh4InfrastructureDataAccessEFSqlServerConfigDataContextObjectContextGenerator.cs:line 32406 at Aseinfo.Infrastructure.Controllers.UserController.Save(Usuario newUser, String username, String codexp, String txtContrasena, String txtConfContrasena, String txtDefaultDomain, Nullable1 iniciaFlujo, Boolean inserting) in C:\vh4\Infrastructure\Controllers\UserController.cs:line 549 at Aseinfo.Infrastructure.Controllers.UserController.Edit(Usuario newUser, String username, String codexp, String txtContrasena, String txtConfContrasena, String txtDefaultDomain, Nullable1 iniciaFlujo) in C:vh4InfrastructureControllersUserController.cs:line 289 at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c.<BeginInvokeSynchronousActionMethod>b__9_0(IAsyncResult asyncResult, ActionInvocation innerInvokeState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult2.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>cDisplayClass11_0.<invokeactionmethodfilterasynchronouslyrecursive>b0() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>cDisplayClass11_2.<invokeactionmethodfilterasynchronouslyrecursive>b2() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>cDisplayClass11_2.<invokeactionmethodfilterasynchronouslyrecursive>b2() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>cDisplayClass11_2.<invokeactionmethodfilterasynchronouslyrecursive>b2() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>cDisplayClass11_2.<invokeactionmethodfilterasynchronouslyrecursive>b2() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>cDisplayClass11_2.<invokeactionmethodfilterasynchronouslyrecursive>b2() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>cDisplayClass3_6.<begininvokeaction>b4() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>cDisplayClass3_1.<begininvokeaction>b1(IAsyncResult asyncResult)