Russian flight controllers have diagnosed the cause of the false smoke alarm that was triggered in the Pirs docking compartment earlier this morning. The sensor had previously been inhibited after proving to be overly-sensitive to dust particles. There are other sensors in the area that perform normally, however this particular sensor has a history of causing similar false alarms.
When Russian flight controllers rebooted the Zvezda service module central computers, all the sensors were reactivated, including the one that had previously been inhibited. It once again caused a false alarm and has since been re-inhibited.