While trying to migrate imagesets from from namespace A to namespace B the update stop with a ConstraintViolationException exception

While moving imagesets from namespace A to namespace B while using:

context.setName(oldname, newname)

the update process stops with the following exception:

javax.jcr.nodetype.ConstraintViolationException: /content/gallery/images/vb-01-uitgelicht-school.jpg/vb-01-uitgelicht-school.jpg/imageset:thumbnail: mandatory property

data does not exist

See for more information the attached stacktrace