Unfortunytely simply building and uploading the App again might not always work - at least not without some extensive testing and maybe some changes. This is because we now use a new version of Xcode, new Frameworks, new mandatory keys for the Info-plist, etc. Depending of the age of the last App release, there can be a lot of changes which may need attention.

Thank you very much for the clarification. However I think this needs some official documentation. Also it is unclear why this only covers the "App Limits" section of Screen Time and not the very similar content-based restrictions. In both cases the limits are based on the URLs of web sites, so there's no logical difference. If you expose these errors to Apps, they really needs to be documented and "stable". Apps need to know the reason for errors in order to be able to respond correctly.

How does your JavaScript code look like? I guess if the message you post from your JavaScript code can not be converted into a swift-compatible object (like a string, dictionary etc), the "body" might be nil (though according to the API, body is not an optional and therefore can not be nil). This would be a bug in the iOS, however you should be able to make sure that this bug is never triggered: Just make sure your JavaScript code only posts valid objects through the message handler.

Also which object do you release? And when exactly? In general the script message handlers should be set once when creating the WebView and released only before releasing the WebView itself. The JavaScript code is running completely independently from the swift code of your App, so it can be tricky to find the correct time to release the message handler and being sure that it is no longer in use by the JavaScript code.