Unbinds custom data bound controls from the container specified into their underlying BindingSource objects/fields.

If any errors occur during the unbinding - typically formatting errors - these errors are reflected in the bindingErrors collection of the form which is returned also returned as a result value. You can check this as follows:

this.UnbindData();

if (this.bindingErrors.Count > 0)
{
   this.ErrorDisplay.Text = this.bindingErrors.ToHtml();
   return;
}

You can add additional binding errors by using AddBindingError() and AddValidationErrorsToBindingErrors() which adds business object errors to the the BindingErrors collection.