Unable to resolve key: yyyy
Unable to resolve key: yyyy
key(string)
This means a container has failed to resolve a key in the call container.get(key).
This requires specific debugging as it shouldn't happen, with all the default strategies to resolve for various kinds of keys.
Please also note that this error could be caused by a plugin and not your application. After ruling out that the error is not being caused by your code, try removing any registered plugins one at a time to see if the error resolves itself.