Bug 318878 – REGRESSION (Safari 26.5.2): Random page crashes due to invalid IPC message WebResourceLoader_WillSendRequestReply

• Status: RESOLVED
• Resolution: FIXED
• Component: Page Loading

After updating to MacOS/iOS 26.5.2 I have noticed that several websites randomly crashed with the error message "A problem repeatedly occurred with <sitename>.
Visually the page would load just fine but then crash. 
This happened on a MacBookPro M3, MacOS 26.5.2, iPhone SE 2nd gen iOS 26.5.2, both with Safari and Ecosia browser.

Sometimes the same site would work, but other times it wouldn't. 
After debugging, all sites that crash have a pattern of the following logging:


2026-07-08 18:22:22.402336+0200 0x11a22d   Fault       0x854915             69220  14   com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:IPC] /AppleInternal/Library/BuildRoots/4~CSjpugCypH81GiRiC7qjc7h_Ls9vYj2Av51m9vQ/Library/Caches/com.apple.xbs/TemporaryDirectory.QSy8hj/Sources/WebKit/Source/WebKit/NetworkProcess/NetworkResourceLoader.cpp 1450: Invalid message dispatched auto WebKit::NetworkResourceLoader::continueWillSendRedirectedRequest(ResourceRequest &&, ResourceRequest &&, ResourceResponse &&, std::optional<WebCore::PCM::AttributionTriggerData> &&, CompletionHandler<void (WebCore::ResourceRequest &&)> &&)::(anonymous class)::operator()(ResourceRequest &&, bool)
2026-07-08 18:22:22.402420+0200 0x11a22d   Error       0x0                  69220  0    com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:Network] 0x10f235000 - [pageProxyID=5255, webPageID=5309, frameID=4294967812, resourceID=357, isMainResource=0, destination=0, isSynchronous=0] NetworkResourceLoader::didFailLoading: (wasServiceWorkerLoad=0, isTimeout=0, isCancellation=1, isAccessControl=0, errorCode=-999)
2026-07-08 18:22:22.402452+0200 0x11a22d   Default     0x0                  69220  0    com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:Network] 0x10f235000 - [pageProxyID=5255, webPageID=5309, frameID=4294967812, resourceID=357, isMainResource=0, destination=0, isSynchronous=0] NetworkResourceLoader::cleanup: (result=2)
2026-07-08 18:22:22.402504+0200 0x11a22d   Activity    0x854916             69220  0    com.apple.WebKit.Networking: (libsystem_trace.dylib) Activity for state dumps
2026-07-08 18:22:22.402503+0200 0x11a22d   Fault       0x854916             69220  14   com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:IPC] Received an invalid message 'WebResourceLoader_WillSendRequestReply' from WebContent process 977, requesting for it to be terminated.
2026-07-08 18:22:22.402547+0200 0x11a22d   Default     0x0                  69220  0    com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:Loading] 0x10e0923c0 - [webProcessIdentifier=977] NetworkConnectionToWebProcess::removeLoadIdentifier: Removing identifier 364 and aborting corresponding loader
2026-07-08 18:22:22.402557+0200 0x11a22d   Default     0x0                  69220  0    com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:Network] 0x10f227800 - [pageProxyID=5255, webPageID=5309, frameID=4294967812, resourceID=364, isMainResource=0, destination=0, isSynchronous=0] NetworkResourceLoader::abort: (hasNetworkLoad=1)
2026-07-08 18:22:22.402563+0200 0x11a22d   Default     0x0                  69220  0    com.apple.WebKit.Networking: (WebKit) [com.apple.WebKit:Network] 0x10f227800 - [pageProxyID=5255, webPageID=5309, frameID=4294967812, resourceID=364, isMainResource=0, destination=0, isSynchronous=0] NetworkResourceLoader::abort: Keeping network load alive due to keepalive option


This happens all the time a page/site is crashing. Seems that this bug was introduced during the 26.5.2 update as other mac/ios devices on 26.5 and 26.5.1 do not experience this. It happens for most sites where ads / tracking elements are used, eg frequently. Hence my severity critical 

My workaround: use an adblocker premium to prevent the cross-loading

Should be needed, I have several outputs of the command  log stream --level error  --predicate 'process == "com.apple.WebKit.Networking" OR process == "com.apple.WebKit.WebContent"' available

[Radar WebKit Bug Importer]

<rdar://problem/181753576>

If it helps, I made a simple reproduction case: https://testpages.kzar.co.uk/beacon-redirect-block/ . The tracking request to `https://eviltracker.net` needs to be blocked for the crash to be triggered, for example if you load the page with the DuckDuckGo browser that request will be blocked and therefore the tab crashes.

Pull request: https://github.com/WebKit/WebKit/pull/69298

Thank you for the reproduction case! I was able to reproduce the crash with https://testpages.kzar.co.uk/beacon-redirect-block/ on the DuckDuckGo MacOS browser using tip-of-tree WebKit and I've confirmed that the fix I posted above (https://github.com/WebKit/WebKit/pull/69298) makes the crash go away.

Amazing that was quick, thanks for fixing that!

Happy to help!

[EWS]

Committed 317582@main (524399615e24): <https://commits.webkit.org/317582@main>

Reviewed commits have been landed. Closing PR #69298 and removing active labels.

[EWS]

Committed 316606.132@safari-7625-branch (7c8584b727b0): <https://commits.webkit.org/316606.132@safari-7625-branch>

Reviewed commits have been landed. Closing PR #5965 and removing active labels.