Failed to upload the report data - An exception occurred

Ran about 7 hours of tests. At the end received this message: An exception occurred within the TLogObserver handler of the ltcLogData event: Failed to upload the report data.

This happened multiple times. I ran several execution plans on several VM's over night and then again today.

What is happening to cause the issue? Do I have to break up the execution plans smaller than 7 hours?