EDIT
Now a newer admob version is available.
I confirm that using the latest releases (15.0.1 or newer) the issue doesn’t appear anymore, so you can use the latest version of Admob
com.google.firebase:firebase-ads:17.1.2
setting the target version to the latest, if you have used the workaround previously suggested.
———————————————————-
Set the target to Android API Level to 26 to fix the issue, waiting for Admob update
In build.gradle
targetSdkVersion 26
if targetSdkVersion
is >=27 ( > android.os.Build.VERSION_CODES.O
that is 26) you get this error, they have changed ActivityRecord in latest Android version adding this:
void setRequestedOrientation(int requestedOrientation) {
if (ActivityInfo.isFixedOrientation(requestedOrientation) && !fullscreen
&& appInfo.targetSdkVersion > O) {
throw new IllegalStateException("Only fullscreen activities can request orientation");
....
}
The change has been introduced in this commit
Prevent non-fullscreen activities from influencing orientation This
changelist enforces that activities targeting O and beyond can only
specify an orientation if they are fullscreen.
and probably in admob lib have messed some check