A communication device for handling a full configuration, comprising: at least one storage device; and at least one processing circuit, coupled to the at least one storage device, wherein the at least one storage device stores, and the at least one processing circuit is configured to execute, instructions of: establishing a packet data unit, PDU, session identified by a PDU session identity, ID, with a first network node; the communication device being configured with a first data radio bearer, DRB, identified by a first DRB ID and associated to the PDU Session or the PDU session ID, by a first base station, BS, connecting to the first network node; receiving a first radio resource control, RRC, message from the first BS; releasing a first service data adaptation protocol, SDAP, entity associated to the first DRB and releasing at least one of a first packet data convergence protocol, PDCP, entity associated to the first DRB, a first radio link control, RLC, entity associated to the first DRB and a first logical channel associated to the first DRB, when the first RRC message indicates the full configuration and comprises a first DRB configuration, wherein the first DRB configuration comprises a second DRB ID and the PDU session ID; adding a second DRB according to the first DRB configuration and associating the second DRB to the PDU session; and communicating first data associated with the PDU session on the second DRB. at least one storage device; and at least one processing circuit, coupled to the at least one storage device, wherein the at least one storage device stores, and the at least one processing circuit is configured to execute, instructions of: establishing a packet data unit, PDU, session identified by a PDU session identity, ID, with a first network node; the communication device being configured with a first data radio bearer, DRB, identified by a first DRB ID and associated to the PDU Session or the PDU session ID, by a first base station, BS, connecting to the first network node; receiving a first radio resource control, RRC, message from the first BS; releasing a first service data adaptation protocol, SDAP, entity associated to the first DRB and releasing at least one of a first packet data convergence protocol, PDCP, entity associated to the first DRB, a first radio link control, RLC, entity associated to the first DRB and a first logical channel associated to the first DRB, when the first RRC message indicates the full configuration and comprises a first DRB configuration, wherein the first DRB configuration comprises a second DRB ID and the PDU session ID; adding a second DRB according to the first DRB configuration and associating the second DRB to the PDU session; and communicating first data associated with the PDU session on the second DRB. establishing a packet data unit, PDU, session identified by a PDU session identity, ID, with a first network node; the communication device being configured with a first data radio bearer, DRB, identified by a first DRB ID and associated to the PDU Session or the PDU session ID, by a first base station, BS, connecting to the first network node; receiving a first radio resource control, RRC, message from the first BS; releasing a first service data adaptation protocol, SDAP, entity associated to the first DRB and releasing at least one of a first packet data convergence protocol, PDCP, entity associated to the first DRB, a first radio link control, RLC, entity associated to the first DRB and a first logical channel associated to the first DRB, when the first RRC message indicates the full configuration and comprises a first DRB configuration, wherein the first DRB configuration comprises a second DRB ID and the PDU session ID; adding a second DRB according to the first DRB configuration and associating the second DRB to the PDU session; and communicating first data associated with the PDU session on the second DRB.