Problems when try to change attribute propeties

I met a problem when try to change the unit or label of a attribute. Either with JIVE, I got

Or with Pytango using tango.server.Device.set_attribute_config3() or with tango.DeviceProxy.set_attribute_config(), I got

dp = tango.DeviceProxy('sys/tg_test/1')
config = dp.get_attribute_config('ampli')
config.label = "newlabel"
dp.set_attribute_config(config)

Basically same error

PyTango.DevFailed: DevFailed[
DevError[
    desc = Device sys/tg_test/1-> Attribute : ampli
           Database error occurred whilst setting attribute properties. The database may be corrupted.
  origin = Attribute::set_upd_properties()
  reason = API_CorruptedDatabase
severity = ERR]
]