valMinLen and valMaxLen fail validation for objects with mapper string fields that are null. I ran into this problem when reading a User object that has valid null data in some MappedString fields. For example, I have a User object with a MappedString field called ZipCode (not a MappedPostalCode) that was null in the DB. When I tried to update another field on this user, say firstName for example, the null ZipCode failed validation. Here is the original thread on the lift discussion group that I added: http://groups.google.com/group/liftweb/browse_thread/thread/6c9dc59adca8c688/4e562d6584bf6eed

In that thread, David mentions he will modify these methods with a flag to leave the default behavior the same as to not break existing code. Thanks all.