The error message "7f 36 71" occurs when flashing the application using Service 36

[koukoukkk]

I really appreciate the library you developed—it works flawlessly, is smooth, and very stable. However, I’ve encountered an issue during usage and hope you can provide some guidance.

When using ​​CAN FD​​, the flashing process completes successfully. But when using ​​CAN​​, while shorter flash packets (for the driver) work fine, the application flashing fails at the first ​​'36 01...'​​ command, returning an error ​​'36 7f 71'​​. I’ve verified that no '36' service message exceeds the maximum allowed length. I tried increasing the override_receiver_stmin​​ parameter, but it didn’t resolve the issue.

Here is my code:

def server_36(response_34_data,block_data,file_list):
    file_path_list = []
    for file in file_list:
        if file.get("file_type") == "XML":
            file_path = analysis_xml(file.get("file_path"))
            for i in range(len(file_path)):
                file_and_sign_list = analysis_xml(file.get("file_path"))
                file_path_list.append(file_and_sign_list[i][0])
        else:
            file_path_list.append(file.get("file_path"))
    total_steps = calculate_steps(file_path_list)  

    max_36 = (int(eval("0x" + response_34_data)))   
    # print("max_36:>>>>>>>>>>>>>>>>>>>>>>>>>>>>", max_36)
    data_bytes = bytes.fromhex(str(block_data.get("data"))[2:-1])  
    sequence_number = 1  

    while len(data_bytes) > 0:
        chunk_size = min(max_36 - 2, len(data_bytes))
        chunk_data = data_bytes[:chunk_size]  
        data_bytes = data_bytes[chunk_size:]  
        print("chunk_data", chunk_data)
        request = TransferData.make_request(sequence_number=sequence_number, data=chunk_data)

        print("client_before>>>>>>>", client)
        client.send_request(request, timeout=8)
        print("client_end>>>>>>>", client)
        print(f"Sent TransferData (sequence_number={sequence_number:02X}, data_length={len(chunk_data)})")
        sequence_number = (sequence_number + 1) % 0x100  
if __name__ == '__main__':
isotp_params = {
    'stmin': 255,
    'blocksize': 8,
    'wftmax': 4095,
    'tx_data_length': 8,
    'tx_data_min_length': 8,
    'tx_padding': 0xCC,
    'rx_flowcontrol_timeout': 5000000,  # +0
    'rx_consecutive_frame_timeout': 5000000,   # +0
    "override_receiver_stmin": 0.002,  # -0
    'max_frame_size': 4095
}
bus = PcanBus(channel="PCAN_USBBUS1", bitrate=500000)
tp_addr = isotp.Address(isotp.AddressingMode.Normal_11bits, txid=0x7E7,rxid=0x7EF)  # Network layer addressing scheme
stack = isotp.CanStack(bus=bus, address=tp_addr, params=isotp_params)
stack.set_sleep_timing(0.02,0.01)
conn = PythonIsoTpConnection(stack)
with Client(conn, request_timeout=10) as client:

.....
Error message:
2025-07-31 11:14:59 [DEBUG] Connection: Sending 11 bytes : [34104470100000000002d2]
2025-07-31 11:14:59 [DEBUG] Connection: Received 4 bytes : [74200802]
2025-07-31 11:14:59 [INFO] UdsClient: Received positive response for service RequestDownload (0x34) from server.
2025-07-31 11:15:00 [DEBUG] Connection: Sending 2050 bytes : [360191d000f8d9ffb4b....]
2025-07-31 11:15:01 [DEBUG] Connection: Received 3 bytes : [7f3671]
Traceback (most recent call last):
File "E:\v7_last\flashtool\common\can\pcan_uds_new.py", line 343, in
server_36(app_response_34_data, block_data, file_list)
File "E:\v7_last\flashtool\common\can\pcan_uds_new.py", line 154, in server_36
client.send_request(request, timeout=8)
File "C:\Users\741170\AppData\Local\Programs\Python\Python310\lib\site-packages\udsoncan\client.py", line 2339, in send_request
raise NegativeResponseException(response)
udsoncan.exceptions.NegativeResponseException: TransferData service execution returned a negative response TransferDataSuspended (0x71)

[pylessard]

Your device is refusing the request. Check with your device. The issue is not in this project