please help me about abmob interstitial make app crashed on Android

I integrate abmob in my Unity game for Android.
It was totolly OK before I decided to show interstitial in the app.

It always crash after showing the interstitial, this is actually weird. It’s not crash immediately after closing interstitial but it crashed after closing for a few mins later.

Anyone have an idea what wrong with it?

PS .I use GitHub - googleads/googleads-mobile-unity: Official Unity Plugin for the Google Mobile Ads SDK.

I solved it,.
I had the same issue and didn’t find any solution regarding that, but later I tried resolving android jar files using android resolver by right clicking in project window\playServiceResolver\androidResolver\Resolve and after resolution succeeded I build an apk and that runs perfectly.

I have a similar problem. The interstitial shows fine, but if I click on it and later come back to the game and close the Ad then, the app crashes with the same errror message.