Hi, I believe you are experiencing the same issues as discussed here: https://forum.pycom.io/topic/5765/loadprohibited-core-panic-when-initialize-wlan Can you review the discussion? There are of course slight differences between the antennas etc. on the boards (manufacturing tolerances etc) and doing a full erase using the update firmware tool might help in that regard. Let me know!

Hello @iwahdan, I put the LoRa Init after the LTE connection and it works now ! Thank you. Best Regards, Malo

@jmarcelino do you already searching for a solution or have found it ???? I have the same problem

@tobru From memory I think it was a 10k resister - check the spec sheet for the HC-SR04. I probably just attached it straight onto the expansion board, maybe via a breadboard - I can't remember sorry.

@jimpower I think it should work ok with latest releases. However I did not test it for some time.

I just want to remind that this issue remains unsolved on 1.6.13.b1 Counter 1: 10009 Counter 2: 6449 Counter 3: 12757 Counter 1: 10024 Counter 2: 6459 Counter 3: 12778 Counter 1: 10040 Counter 2: 6470 Counter 3: 12798 Counter 1: 10055 Counter 2: 6480 Counter 3: 12818 Counter 1: 10070 Counter 2: 6490 Counter 3: 12838 Counter 1: 10086 Counter 2: 6501 Counter 3: 12858 Counter 1: 10101 Counter 2: 6511 Counter 3: 12878 Counter 1: 10116 Counter 2: 6521 Counter 3: 12899 Counter 1: 10132 Counter 2: 6531 Counter 3: 12919 Counter 1: 10147 Counter 2: 6541 Counter 3: 12939 Guru Meditation Error of type InstrFetchProhibited occurred on core 0. Exception was unhandled. Register dump: PC : 0xffffffff PS : 0x00060a30 A0 : 0x800eb2f0 A1 : 0x3ffe1f50 A2 : 0x3ffe28d0 A3 : 0x00000001 A4 : 0x00000000 A5 : 0x3ffe1f70 A6 : 0x00050823 A7 : 0x00000000 A8 : 0x800eb2ac A9 : 0x3ffe1f30 A10 : 0x3ffe28d0 A11 : 0x00000001 A12 : 0x00000000 A13 : 0x3ffe1f70 A14 : 0x00000003 A15 : 0x00060823 SAR : 0x00000012 EXCCAUSE: 0x00000014 EXCVADDR: 0xfffffffc LBEG : 0x400f753a LEND : 0x400f7543 LCOUNT : 0x00000000 Backtrace: 0x7fffffff:0x3ffe1f50 0x400eb2f0:0x3ffe1f70 0x400dccb8:0x3ffe1fa0 0x400e1672:0x3ffe1fc0 0x400d8244:0x3ffe2050 ================= CORE DUMP START ================= ...