Rewarded ad load failures caused by "Unable to obtain a JavaScriptEngine" on Android

[A lan (Alan)]

Hi everyone,

We are seeing frequent rewarded ad load failures on Android with the following error:

"Unable to obtain a JavaScriptEngine"

Context:
- Platform: Android
- Ad format: Rewarded Ads
- Google Mobile Ads SDK: 24.8.0
- App is published on Google Play
- MobileAds initialization succeeds
- Rewarded ad load fails on a subset of devices, repeatedly on the same users

What we have observed:
- The majority of failures (>70%) are caused by "Unable to obtain a JavaScriptEngine"
- The issue is device-specific, not global
- We logged the system WebView provider using WebView.getCurrentWebViewPackage()
- Failures are correlated with certain WebView providers (e.g. Android System WebView / Chrome)
- No android:sharedUserId is used, and the app is not a system app
- Using official test ad unit IDs shows the same behavior on affected devices

What we have tried:
- Verified SDK integration and permissions
- Tested with official AdMob test ad units
- Confirmed the issue does not occur on most devices
- Confirmed this is not a "no fill" issue

Questions:
1. Is "Unable to obtain a JavaScriptEngine" considered a device-level WebView / JS environment issue outside of the app’s control?
2. Are there any recommended best practices for handling this case (e.g. session-level blocking, retry limits, or user guidance)?
3. Is it acceptable to stop requesting rewarded ads for the current session after encountering this error to avoid repeated failures?

Any confirmation or guidance from Google engineers or experienced developers would be greatly appreciated.

Thanks in advance.