Even though amazon’s error doesn’t give much information as to why the user is unable to use the API, maybe the plugin could be updated to suggest to the user that he may need to sign the usage agreement when it gets this “InternalError”. That would be awesome.
I am experiencing the same problem. I’m not willing to downgrade from 3.4.1 to see if that will help, so I wonder when this will fix itself or if the plugins will need to be updated….
