UPDATE - i found the problem. I had password protected the import site's main directory which caused the error.
My mistake - thank you for this plugin - it has saved me tons of work since i have a master site and multiple slave sites that share the same widgets.
Below is a link to a recently resolved post however I don't think this is an edge case.
I am getting the same error when trying to export from one subdomain to another. Each subdomain contains its own web site, which is a valid situation.