Peer manager, bonding fails with error code 133

Question

I am working on two devices, a peripheral and a central. The peripheral is custom hardware. The central is being run on a Rigado BMD-300 series evaluation kit. I'm using Segger IDE and NRF5 SDK 16.

I can get the central and peripheral to pair consistently. Discovery works and the central sees the characteristics (and changes) correctly. Now I'm working on bonding and whitelisting.

After discovery is complete (in the discovery event handler), I am calling pm_conn_secure():

// Initiate bonding.
ret_code_t err_code = pm_conn_secure(p_evt->conn_handle, false);
NRF_LOG_DEBUG("Called pm_conn_secure, conn_handle = %d, err_code = %d", p_evt->conn_handle, err_code);
if (err_code != NRF_ERROR_BUSY)
{
  APP_ERROR_CHECK(err_code);
}

which returns NRF_SUCCESS. Quickly thereafter, I get a PM_EVT_CONN_SEC_FAILED event in the Peer Manager event handler. In the logs, I see the following:

changes to <debug> app: Called pm_conn_secure, conn_handle = 0, err_code = 0

<debug> nrf_ble_gq: Processing the request queue...

<info> peer_manager_handler: Connection security failed: role: Central, conn_handle: 0x0, procedure: Bonding, error: 133

<debug> app: Got PM_EVT_CONN_SEC_FAILED event

<debug> nrf_ble_gq: Processing the request queue...

Questions:

1) Is there something I have to do in the peripheral to allow bonding?

2) Any ideas on what could be causing this?

Vidar Berg · Accepted Answer

Thanks for confirming. So the error response is most likely coming from the peer manager then. The usual reason for this is that an already bonded client tries to send a new pairing request to the peripheral. Please try to erase all bonds on the peripheral and repeat the test to see if you get the same error. 
 How the Softdevice event forwarding works is explained in more detail here SoftDevice Handler library , but it sounds like it is working in your case. 
 And here is another relevant thread if you want to accept bond update requests: https://devzone.nordicsemi.com/f/nordic-q-a/51965/pairing-and-bonding-after-deleting-synchronization 
 Edit: 
 jbmillard said: Again, how do I tell if nRF Connect is bonded? 
 It depends on what platform you run it on. On Android it will say "BONDED" in the top left corner in the device view. This information is not available in the iOS version, but bonded devices will stay in the "My device" list in settings->Bluetooth even when it's disconnected.

Peer manager, bonding fails with error code 133

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