In R156 we have updated the Mobile Advert plugin on Android to use version 18 of the AdMob SDK. This change is due to hit the stable channel soon, and after talking to a few confused users I wanted to clarify a problem they have been experiencing.
With this update to the SDK comes the requirement that the AdMob App ID must be specified at build time. To comply with this it is now required that you specify your Android App ID in the Mobile Advert plugin properties. If you do not specify it the project will fail to build ( this may change ) and if you choose an invalid value for your app ID the application will be crashed by the SDK on startup.
Edit: For reference your "Admob App ID" is not the same as the value you use with Google play known as the "app ID" or "package ID". The sample ID that admob gives is
"ca-app-pub-3940256099942544~3347511713" so it should resemble that. Admob provides this support article on finding your Admob app ID.
Some of you will be using the "Configure" action to set up the plugin, while it is not marked as so yet this is effectively depreciated going forwards. The plugin will perform this step for you at start up if the application ID is specified. I know some people have been using this to avoid showing the user consent dialog to users immediately, if you want to avoid this then you can change the "Locations to show user consent dialog" property to "nowhere" and call the "Show User consent dialog" action when you wish to trigger it.
Versions prior to r156 are not affected by these changes and will not be changed by future revisions. For those of you also building for iOS we haven't updated the SDK version on iOS yet, but it will have a similar requirement once we have. Once the update for iOS is completed it will not affected releases of construct prior to that update being published.
We intend to add additional checks to the editor to improve the experience around this going forwards, but this will occur during the next beta cycle.
You can read about the change to the Admob SDK here. If you have any issues with the change, or questions then let me know.
Edit: on the first of July we updated the build server to give a more descriptive warning if your application ID is absent. This will only warn you if it is absent, not if it is invalid. Additionally we resolved an issue where iOS builds did not work unless the Android App ID value was specified.