./pcap-decrypt.py capture.pcapng.gz error

[borewicz9]

Traceback (most recent call last):
  File "./pcap-decrypt.py", line 67, in <module>
    args.pcapfile, display_filter=("udp.port == 54321"))
  File "/usr/local/lib/python3.5/dist-packages/pyshark/capture/file_capture.py", line 47, in __init__
    raise FileNotFoundError(str(self.input_filename))
FileNotFoundError: capture.pcapng.gz

Hello, Need help with above error

[igoro00]

i think you should generate this using wireshark Run wireshark for a while and save it to a file