Hi,
I did run into exactly the same issue here today. I am running 2.0.51beta since March, it worked fine. After a period not using Duplicati any more, I tried to reactivate it and now got this error.
The problem is also described in this thread:
In both threads I could not find a solution for it. Neither repairing the installation or uninstalling and re-installing fixed the issue. Any ideas how to solve it?
Thanks a lot in advance!