It looks like connectivity issue. I am suggesting you to verify the network connectivity and its speed to let the destination server to download the files from source server.
Yes, and I asked support to Parallels (ticket #1976368) and after 14 hours they told me is a problem in the source server without any reasonable solution... they suggested the following:
1. Create a new ticket for the source server issue with Urgent severity. Once the source server is up and running, you can reopen this case for migration.
2. As discussed, follow the below KB article to transfer the data using below KB article. http://kb.odin.com/en/123170
The problem is the source server was UP AND RUNNING..... Now it has several problems related to databases. Really I don´t understand Parallels support service...
I have escalated this Support ticket. Please provide them all requested information that was asked in their last reply. They should process this problem.