The embodiments herein relate to a method performed by a gateway (108, 110, 1308, 1310). The gateway (108, 110, 1308, 1310) detects that a procedure for activating or deactivating a bearer has been initiated. The gateway (108, 110, 1308, 1310) receives a first modify bearer or modify access bearers request message for the same PDN connection and UE (101) as the bearer activation or deactivation procedure is intended for. The gateway (108, 110, 1308, 1310) detects a bearer mismatch between a first set of bearers and a second set of bearers known by the gateway (108, 110, 1308, 1310) and associated with said same PDN connection and UE (101). The gateway (108, 110, 1308, 1310) accepts, during a time interval, the received modify bearer or modify access bearers request message even though the bearer mismatch has been detected.