iOS issue when restorting app from background (screen stays white)

[TobiasSchikora]

Hi everyone,

we originally managed our app with cordova. A few months ago we migrated to capacitor. However, we're having a really frustrating problem under iOS:

When you put the app in the background on iOS and then bring it back to the foreground after a while, the screen stays completely white and the app is no longer visible. The only way to fix it is to quit and restart the app. This makes the app very difficult to use for our iOS users. I think the problem is that the app isn't restoring properly from the frozen state.

Has anyone else had a similar problem? Can you give us any helpful tips on how to fix it? We'd really appreciate it if we could get this resolved as soon as possible. It's a very urgent issue.

Thanks for any help!

[jfmaeck]

We are experiencing exactly the same problem (we also migrated from cordova to capacitor). Unfortunately, I haven't found the root cause, yet.

[jfmaeck]

FYI: We fixed it by making "webview reloads" work, see #7097 (comment)

[okletstryit]

Same problem here, latest capacitor behaves the same on iOS

[fbuland]

Same problem on iOS with Capacitor 5.0.0

Issues reported on iOS 16 and iOS 17.

Difficult to reproduce (after several hours and with dozens of other apps open to make pression on memory), XCode logs :

2024-02-23 15:55:46.448139+0100 App[2901:90896] [Process] 0x115000470 - NetworkProcessProxy::didClose (Network Process 0 crash)
2024-02-23 15:55:46.460070+0100 App[2901:90896] [Process] 0x11407c380 - GPUProcessProxy::didClose:
2024-02-23 15:55:46.460863+0100 App[2901:90896] [Process] 0x11407c380 - GPUProcessProxy::gpuProcessExited: reason=Crash
2024-02-23 15:55:46.461080+0100 App[2901:90896] [Process] 0x115001560 - [PID=2904] WebProcessProxy::gpuProcessExited: reason=Crash
2024-02-23 15:55:46.468817+0100 App[2901:90896] [Process] 0x115001560 - [PID=2904] WebProcessProxy::didClose: (web process 0 crash)
2024-02-23 15:55:46.468886+0100 App[2901:90896] [Process] 0x115001560 - [PID=2904] WebProcessProxy::processDidTerminateOrFailedToLaunch: reason=Crash
2024-02-23 15:55:46.469550+0100 App[2901:90896] [ProcessSuspension] 0x114020120 - ProcessAssertion: Failed to acquire RBS Background assertion 'XPCConnectionTerminationWatchdog' for process because PID 0 is invalid
2024-02-23 15:55:46.469971+0100 App[2901:113803] [ProcessSuspension] 0x114020120 - ProcessAssertion::acquireSync Failed to acquire RBS assertion 'XPCConnectionTerminationWatchdog' for process with PID=0, error: (null)
2024-02-23 15:55:46.473957+0100 App[2901:90896] [Process] 0x105838218 - [pageProxyID=8, webPageID=9, PID=2904] WebPageProxy::processDidTerminate: (pid 2904), reason=Crash
2024-02-23 15:55:46.494478+0100 App[2901:90896] [Loading] 0x105838218 - [pageProxyID=8, webPageID=9, PID=2904] WebPageProxy::dispatchProcessDidTerminate: reason=Crash
2024-02-23 15:55:46.538444+0100 App[2901:90896] applicationWillEnterForeground (NB : added log on AppDelegate.swift)
2024-02-23 15:55:46.728490+0100 App[2901:90896] applicationDidBecomeActive (NB : added log on AppDelegate.swift)
⚡️  [log] - onscript loading complete
⚡️  WebView loaded
⚡️  [log] - Ionic Native: deviceready event fired after 121 ms
⚡️  [log] - Ionic Native: deviceready event fired after 107 ms
⚡️  To Native ->  FirebaseAuthentication addListener 3595928
⚡️  To Native ->  App addListener 3595929
⚡️  To Native ->  App addListener 3595930
2024-02-23 15:56:16.470964+0100 App[2901:90896] Could not signal service com.apple.WebKit.WebContent: 113: Could not find specified service

[fbuland]

I'd successfully reproduce the issue with XCode and Simulator.
I followed the explanation at https://stackoverflow.com/questions/71350041/is-webviewwebcontentprocessdidterminate-ever-called-for-an-app-running-in-the-ba

1. Put app to background
2. kill Webkit.WebContent process
3. put app to foreground : white screen

Capacitor WebViewDelegationHandler.swift correctly received webViewWebContentProcessDidTerminate() sent by iOS, and do a webview.reload(). A new Webkit.WebContent process is launched. But still white screen !

I don't know how to investigate more.

[viananicolas]

I've been having this same issue on a Ionic Cordova project that hasn't been migrated to capacitor yet, so the issue doesn't seem to be capacitor specific.

[jfmaeck]

If an application is rewriting the url (e.g. using history.pushState) then a "reload" of this app (e.g. after the web view crashed) results in a 404 blank screen.

If manually reloading the page (location.reload()) results in a white screen, then this might be the case.

Hope this helps.

[fbuland]

Thank you for the tip.

In my case, I reproduced the white screen event if I didn't navigate throw the app.

Do you have a tip to catch errors in the page when playing the app in the XCode App Simulator ?

[jfmaeck]

Sometimes the url gets rewritten even before you explicitly navigate within your app.
In our Angular application we had to set the useHash option of the routerModule to true AND we had to explicitly set the base href to "/index.html" to fix this issue:

npx ng build --base-href='/index.html' --configuration production

(or set it in angular.json)

@NgModule({
  imports: [
    RouterModule.forRoot(routes, {
      useHash: true,
    }),
  ],
  exports: [RouterModule],
})
export class AppRoutingModule {}

[fbuland]

I tried with your indication, but I still reproduce the white screen issue.

[DJStatikVX]

Same problem here, reported by user but I couldn't reproduce it. Hope someone can look into a standard solution soon.

[grzegorzCieslik95]

Same problem here. Do you have any idea how can I fix it? Many of my users reported this error.

[JackBatty98]

Same problem here too, i have tried killing the webview but the app starts up fine afterwards. Its only when its left for long periods of time, for example overnight that this happens.

[TobiTobsn007]

I had this problem too. I detected that in some states, the routing module is not ready and a defined route is not known.
My solution was to define a default / fallback route in every route module.
Second: on NgDestroy methods I removed some listeners which din't exists in some situations. (Unhandled exceptions)
Solution check if objects exists before cleanup. Or handle ist with try catch. Since I fixed this problems, I never had a white screen anymore.
Good luck!