MGC uses Google Custom Search to search for covers & screenshots.
By default MGC is using a shared api key for all users and this can result in the daily quota being reached.
It is thus recommended to request your own (free) API key and not be limited by other users.

Start @ https://console.developers.google.com/project (Click the globe icon on settings)
* Click 'Create project'
* Enter a name in the dialog
* Click 'create'

Open the newly created project (if not already open)
* Click 'Enable and manage APIs'
* Click 'Custom Search API'
* Click 'Enable'

Click on 'Credentials' (Left menu)
* Click 'Create credentials'
* Choose 'API Key'
* Choose 'Android'
* Click 'Create'

Enter the given Api key in MGC