Wireshark · Wireshark-users: [Wireshark-users] Pcap file isn't a capture file in a format TShark understands

[kahou lei <kahou82@xxxxxxxxx>]

Hi,

I am using an EL3 machine and would like to translate some pcap files into pdml format. However, when I type this command:

tshark -r udp.pcap -T pdml >temp.pdml

I got this error:

tshark: The file "udp.pcap" isn't a capture file in a format TShark understands.

I also try 

tcpdump -r udp.pcap

and I got this error:

tcpdump: bad dump file format

Looks like I have an invalid file format. 

Can someone please advice what I should do in order to fix this?

Thanks,
Kahou