No fill and internal server error problems

[Nik Z]

Hi,

I've been having intermittent issues with loading interstitial ads on certain Android devices. The app has been working fine previously but I noticed it started failing late February this year. As the implementation has remained unchanged during that period I switched to using Google's demo ad units (https://developers.google.com/admob/android/test-ads#demo_ad_units) to rule out any issues with the account

://developers.google.com/admob/android/test-ads#demo_ad_units

. The issue still persists even when using test ads.

The error I see in logs is simply "Ad failed to load : 3". The full error returned still doesn't return much useful info:

{
  "Code": 3,
  "Message": "No fill.",
  "Domain": "com.google.android.gms.ads",
  "Cause": "null",
  "Response Info": {
    "Response ID": "2wSeZrj2OpC31fAPn5PJ-Q0",
    "Mediation Adapter Class Name": "",
    "Adapter Responses": [
      {
        "Adapter": "GADMAdapterGoogleAdMobAds",
        "Latency": 0,
        "Ad Source Name": "Reservation campaign",
        "Ad Source ID": "7068401028668408324",
        "Ad Source Instance Name": "[DO NOT EDIT] Publisher Test Interstitial",
        "Ad Source Instance ID": "4665218928925097",
        "Credentials": {
          "pubid": "ca-app-pub-3940256099942544\/1033173712\/cak=no_cache&cadc=76&caqid=2wSeZuP1OYbe1fAP3MmKsAY",
          "campaign_type": "1",
          "campaign_id": "1565349800"
        },
        "Ad Error": {
          "Code": 0,
          "Message": "Internal error.",
          "Domain": "com.google.android.gms.ads",
          "Cause": "null"
        }
      }
    ],
    "Response Extras": {
      "mediation_group_name": "Campaign"
    }
  }
}

I got the same result (Ad failed to load: 3) using interstitial example app from Github: https://github.com/googleads/googleads-mobile-android-examples/tree/main/kotlin/admanager/InterstitialExample which would rule out the problem with the app itself.

I've done some research so far but I seem to have reached a dead end. Here's what I know so far:

• Most of the time this appears on devices with Android 12, 13, 14 though I have seen a single case of this error also happening on Android 11
• No matter how many times the app is restarted or the ad load is retried on a problematic device, it will always return the same error
• I don't have a physical access to any of the devices that are failing but I have tried using example app on several Android devices running Android 13 and could not reproduce this issue
• Not all devices running newer Android versions are affected, on some of them it runs fine.

I suspected that this might be related to some device-specific settings however I have no idea what setting could be causing such an issue. Is there any way to get more data on what exactly is the "internal server error"?

Thanks