AdMob no fill - Could not instantiate mediation adapter: com.google.DummyAdapter

Question

My app uses only AdMob. It is the only "mediation source" as displayed in AdMob mediation settings. AdMob banners are loaded fine, but not interstitials:

I/Ads: Starting ad request.
I/Ads: Trying mediation network: 
I/Ads: Instantiating mediation adapter: com.google.DummyAdapter
W/Ads: Could not instantiate mediation adapter: com.google.DummyAdapter. com.google.DummyAdapter
I/Ads: No fill from any mediation ad networks.
W/Ads: Failed to load ad: 3

What is DummyAdapter? No mediation adapters are used in my app.

Answer 1

I've read different answers to the same problem. The error with code 3 is the one that is returned when admob can't find an ad to send to the app. This can mean a lot of thinks... I know. This problem has occurred in my project using a SMART_BANNER on a Nexus 5 device (it worked on the Samsung Galaxy tab). I've noticed that in these days the style of the test banners have been changed so, maybe, this could be due to some new admob behavior (or bug). Anyway... Using the AdSize.BANNER instead of the AdSize.SMART_BANNER has solved the problem for me.

I don't know if there's any constraint about the usage of the SMART_BANNER (If you read the developers' guide there's no particular constraint about the usage of this type of banner).

Maybe it's just an admob bug or maybe it doesn't work until you use real banners instead of test banners, I don't know.

Hoping my experience will be useful,

Luca