[Webkit-unassigned] [Bug 256219] New: iOS/iPadOS 16.4 with web content filters enabled (Screen time or MDM) causes PWA to show blank white page when loading

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=256219

            Bug ID: 256219
           Summary: iOS/iPadOS 16.4 with web content filters enabled
                    (Screen time or MDM) causes PWA to show blank white
                    page when loading
           Product: WebKit
           Version: Safari 16
          Hardware: iPhone / iPad
                OS: iOS 16
            Status: NEW
          Severity: Major
          Priority: P2
         Component: Service Workers
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: jascolley at yahoo.com

We have a PWA that utilizes services workers. Our users started reporting an issue after updating to iPadOS 16.4 or 16.4.1 where the application would no longer launch from home screen. Instead it would just show a blank white page. It also happens when trying to hit the PWA in Chrome and Safari when not added to home screen. We inspected the application using a Macbook and can see the request going through the service worker like we expect, however it is just returning empty html, head, and body tags when completing the fetch. In the network tab we only see the one request going through the service worker instead of the additional second request to the web server that we would normally expect to see. There are no errors anywhere and nothing else to analyze/try. This seems to be a widespread issue as we have found other posts regarding this. Here are a few of those - 


https://stackoverflow.com/questions/75943170/progressive-web-app-pwa-fails-in-ios-16-4

https://stackoverflow.com/questions/75885199/vue2-pwa-is-not-working-on-ios-16-4-devices?noredirect=1&lq=1

Also, this is reproducible with Spotify PWA we noticed too. If you navigate to https://open.spotify.com and add that URL to home screen on an iPad running 16.4 or later (we have 16.4.1 installed), then try to launch the spotify app from home screen you will see the blank white page. 

To reproduce the blank white page you will need to enable the web content filters by navigating to Settings -> Screen Time (turn on) -> Content & Privacy Restrictions -> Enable Content & Privacy Restrictions -> Content Restrictions -> Web Content -> Select Limit Adult Websites OR Allowed Websites (even with all PWA URLs entered in allowed websites it still fails). After enabling these settings then attempt to launch the Spotify from home screen.

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