< "A" fatal error occurs while processing MTU extension. 
  "A" sdk12.3(s132_nrf52_3.1.0_softdevice.hex) 52832 Peripheral function
  "B" sdk15.2 52832 Central function >
  
 0> SDH:DEBUG:sd_ble_enable: RAM start at 0x200056a8
 0> APP:INFO:charge Example
 0> APP:INFO:Start scanning for device name Cretam_Safety.
 0> APP:INFO:Fast Advertising
 0> APP:INFO:Multilink Example
 0> APP:INFO:Peripheral connected
 0> BLE_GATT:INFO:on_connected_evt(nrf_ble_gatt_t * p_gatt, ble_evt_t * p_ble_evt)
 0> BLE_GATT:INFO:request ATT MTU 64 for conn_handle 0 
 0> APP_ERROR:ERROR:Fatal
=====================================================
< "A" sdk12.3(s132_nrf52_3.1.0_softdevice.hex) 52832 Peripheral function
  "B" nRFTool -> UART on smartphone >
  
0> APP:INFO:Peripheral connected
 0> BLE_GATT:INFO:on_connected_evt(nrf_ble_gatt_t * p_gatt, ble_evt_t * p_ble_evt)
 0> BLE_GATT:INFO:request ATT MTU 64 for conn_handle 0 
 0> BLE_GATT:INFO:EXCHANGE_MTU_RSP effective ATT MTU is 64 for conn_handle 0 
 0> APP:DEBUG:ATT MTU exchange completed. central 0xf7 peripheral 0x40
===================================================== 
 <   "B" sdk15.2(s132_nrf52_6.1.0_softdevice.hex) 52832 Central log >
 
 <debug> ble_scan: Connecting
 0> <debug> ble_scan: Connection status: 0
 0> <debug> nrf_ble_gatt: Requesting to update ATT MTU to 100 bytes on connection 0x0.
 0> <info> app: Connection 0x0 established, starting DB discovery.
 0> <debug> ble_db_disc: Starting discovery of service with UUID 0x1 on connection handle 0x0.
 0> <info> app: Start scanning for device name SafetyElectronic.
 0> <debug> ble_scan: Scanning
 0> <debug> nrf_ble_gatt: Peer on connection 0x0 requested an ATT MTU of 64 bytes.
 0> <debug> nrf_ble_gatt: Updating ATT MTU to 64 bytes (desired: 100) on connection 0x0.
 
 0> <info> app: LBS central link 0x0 disconnected (reason: 0x8)
 0> <info> app: Start scanning for device name SafetyElectronic.
 0> <debug> ble_scan: Scanning

