Yes, I believe I've found a workaround!
I have had the very same problem with my G70 receiver.
Tried updating the firmware from 1.03 to 1.05 on two Macs, a MacBook Pro and a MacBook Air.
Reconnecting, power off and back on, restarting the Line6 updater app, performing a factory reset on the receiver etc. did not resolve the problem.
I would receive the same error message every time.
This morning I had access to a Windows laptop running Windows 7.
After installing the V1.11 Line6 updater app I was able to update the firmware to V1.05 on my G70 receiver.
Maybe the above described update problems are isolated to the Line6 updater app for Mac?
