Hi I have a similar issue and the same errors as you but I am still on OH2.3 using a Raspberry Pi.
I noticed it start a few weeks ago and thought is was my setup.
It also prevents Paper UI loading the Controls tab so I cant check what Things have been created easily.
The addon folder only has one Amazon file amazoncontrol2.4.jar dated 26/11/18.
I deleted all the Amazon Things from Paper UI, uninstalled the binding and restarted OH.
I downloaded the latest beta from as detailed here https://community.openhab.org/t/released-openhab2-amazon-echo-control-binding-controlling-alexa-from-openhab2/37844
and restarted OH using
sudo systemctl restart openhab2.service
Note: if you are using the amazon.jar in the addons folder you don’t need to add the binding in Paper UI.
I then checked the Amazon Things in Paper UI and updated my sitemap as the amazon account ID had changed. I also needed to enable the extra Channels in Paper UI > Configuration > Things > “Echo name”.
Once all that was done I didn’t get the error.