Problem with saving “Google Access Code”

Hi, we are currently experiencing some troubles with your plugin.
We tried and install it in our dev environment where it works perfectly fine, on the live-stage i can’t save the “Google Access Code” it results on “Access code Can’t be blank” after some debugging i was able to get the source of the error, after pressing “Save” the ajax response is unsuccessfull and returns:

“Error thrown
Call to undefined method GuzzleHttp\Utils::chooseHandler()”

Can you help me with this specific problem? Besides that we are very happy with your plugin. Thanks in advance!