PM_CONN_SEC_ERROR_SMP_TIMEOUT

#define PM_CONN_SEC_ERROR_SMP_TIMEOUT   (PM_CONN_SEC_ERROR_BASE + 0x101)

#include <peer_manager_types.h>

Pairing/bonding could not start because an SMP time-out has already happened on this link. This means that no more pairing or bonding can happen on this link. To be able to pair or bond, the link must be disconnected and then reconnected. See Bluetooth Core Specification 4.2 section 3.H.3.4 (@linkBLEcore).