Hi Kent,
Thank you for contacting the Mobile Ads SDK Support team.
Error code 3, no fill error means that the ad request was successful, but no ad was returned due to lack of ad inventory. Kindly do note that the SDK just requests ads to the ad server and does not have any control on the ads it serve this behavior isn't controlled by the Mobile Ads SDK.
Make sure that you have followed the Android implementation guidelines. This is more of an Ad serving concern rather than anything specific to the code implementation of the Mobile Ads SDK. I would recommend that you refer to AdMob Error Codes & Logs for more details about the issue.
In the event that the issue continues to occur, could you kindly provide us with the following information to allow us to conduct a review of the code implementation? We will endeavor to replicate the issue from our perspective.
![]() |
Mobile Ads SDK Team |