We are using Vector CAN Flash DC 2.4 to load software (.mot) file into our Electronic Control Unit (ECU).

I invoke this tool.  Say 'yes' to Disclaimer.  Open CAN Database (.dbc file).  Right-click on opened database.  Click on "Download File".
A window opens with Vector: Flash Attributes DC 2.4.  I click Next.  I add Application File (.mot file).  Click Next and attached error pops
up.

What might be causing this error?
CAN Flash Error.JPG

Unfortunately, I am not an expert on the specific tool you are using.  However, with similar tools, this kind of error is generally due to poor cabling and/or electrically noisy environment.  I would start from that.

Ivan