On what basis UE rejects the RRC connection reconfiguration?

Question

During attach procedure, UE sends "Attach Request" along with "RRC Connection Setup Complete", eNodeB sends "Attach Accept" along with "RRC Connection Reconfiguration then why UE does not send "Attach Complete" along with "RRC Connection Reconfiguration Complete" message ? What could be the reason for defining the messages so ?

Answer 1

-if the UE is unable to comply with (part of) the configuration included in the RRCConnectionReconfiguration message:
-if security has not been activated:

NOTE 1: The UE may apply above failure handling also in case the RRCConnectionReconfiguration message causes a protocol error for which the generic error handling as defined in 5.7 specifies that the UE shall ignore the message.
NOTE 2: If the UE is unable to comply with part of the configuration, it does not apply any part of the configuration, i.e. there is no partial success/ failure.

Ref : 331>5.3.5.5 Reconfiguration failure

Answer 2

If UE not able to attach with tenb i.e RACH procedure fails and UE not able to comply with configuration given by Senb