Import Error unparsable content detected

Hello, create BPMN model online on your website. Save it on my computer. And then try to open it once again and recived next message:

unparsable content detected
line: 0
column: 0
nested error: missing start tag

What does it mean? Link on the file in Att. The file is very important for me.
Thanks in advanced.

Not sure what you uploaded but the attached file is empty.

Yes, I’ve thought the same too, but I open this file from other computer, and the message was not the same
The photo is in att.