How to handle WKWebView Errors after ios memory pressure ?

[Nikita-schetko]

After some time in background and under memory pressure from other apps in ios i get following errors (Gathered during app debug in XCode):

2021-11-19 12:35:12.480673+0300 App[4121:1313634] [Process] 0x1061bc600 - [PID=4123] WebProcessProxy::didClose: (web process 0 crash)
2021-11-19 12:35:12.481699+0300 App[4121:1313634] [Process] 0x1061bc600 - [PID=4123] WebProcessProxy::processDidTerminateOrFailedToLaunch: reason=4
2021-11-19 12:35:12.483202+0300 App[4121:1313634] [ProcessSuspension] 0x1061d4b40 - ProcessAssertion: Failed to acquire RBS Background assertion 'ConnectionTerminationWatchdog' for process because PID is invalid
2021-11-19 12:35:12.483748+0300 App[4121:1314263] [ProcessSuspension] 0x1061d4b40 - ProcessAssertion: Failed to acquire RBS assertion 'ConnectionTerminationWatchdog' for process with PID=0, error: (null)
2021-11-19 12:35:12.491589+0300 App[4121:1313634] [Process] 0x102839c18 - [pageProxyID=5, webPageID=6, PID=4123] WebPageProxy::processDidTerminate: (pid 4123), reason 4
2021-11-19 12:35:12.523850+0300 App[4121:1313634] [Loading] 0x102839c18 - [pageProxyID=5, webPageID=6, PID=4123] WebPageProxy::dispatchProcessDidTerminate: reason=4
2021-11-19 12:35:12.526025+0300 App[4121:1314263] [assertion] Error acquiring assertion: <Error Domain=RBSAssertionErrorDomain Code=2 "Specified target process does not exist" UserInfo={NSLocalizedFailureReason=Specified target process does not exist}>
2021-11-19 12:35:12.526090+0300 App[4121:1314263] [ProcessSuspension] 0x1061d4ba0 - ProcessAssertion: Failed to acquire RBS assertion 'NetworkProcess Background Assertion' for process with PID=4124, error: Error Domain=RBSAssertionErrorDomain Code=2 "Specified target process does not exist" UserInfo={NSLocalizedFailureReason=Specified target process does not exist}
2021-11-19 12:35:12.585375+0300 App[4121:1313634] [Process] 0x106164190 - NetworkProcessProxy::didClose (Network Process 0 crash)
:zap:️ TO JS {"isActive":true}






Is it possible somehow to handle it and make some required actions? For example, show splash screen again, before app actually will be reloaded ?




Why app in this case not fully reloaded, but reloaded only content in WKWebview ?



Currently, after that kind of situation, i see white screen for a while (like 'new tab' in a safari) before actual re-load of my app. 

Is there is any option to show default splash screen during that kind of situations?

[JornHermans]

Same issue, do you have any solution.

[realityfilter]

Sam issue here. Did anybody find a solution, yet?

[lj-dickey]

Having the same issue, and found the WKNavigationDelegate function webViewWebContentProcessDidTerminate, which is indeed called when the web processes crash in our app. I'm hoping that I can add code in those functions that will cause the app to reload the WebViews (which are loaded from strings initially, so just calling reload on the WKWebView doesn't do anything, presumably because the DOM disappeared when the web proxy process crash).

[KevinKelchen]

FYI, as mentioned here and referred to here, Capacitor 3.4.1 adds back the code that reloads the WebView if it's been terminated.

This still results in the white screen during the reload with no splash screen though. I think that's because the WKWebView is running as a separate process, and it's the overall native app process (the "shell") that triggers the splash screen to appear when it starts up. If, for example, the entire native app process (not just the WKWebView) is killed while being backgrounded, then after bringing the app to the foreground the splash screen would likely appear again.

This issue, which I linked to above, is about a feature request to notify the JS layer about a WebView reload. While you might be able to use JS to show the splash screen again, it very likely wouldn't be early enough to prevent some of the white screen from showing since the reload would by necessity occur before the JS could even load. I would think something like that may have to be handled in native code before the call to the WebView reload occurs.

I might reply to the issue about what we're doing in our app. We're customizing Capacitor code where webViewWebContentProcessDidTerminate is called so we can know if the reload occurs. It would be nice if that callback were extensible similar to how a Custom ViewController is an extension point.

[KevinKelchen]

I posted a Q&A Discussion item related to detecting the involuntary reload for anyone who's curious.

[esam12]

Same issue, do you have any solution.
#flutter #ios