General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Wi-Fi (general): How to modernize your captive network developer news post Wi-Fi Fundamentals forums post Filing a Wi-Fi Bug Report forums post Working with a Wi-Fi Accessory forums post — This is part of the Extra-ordinary Networking series. Wi-Fi (iOS): TN3111 iOS Wi-Fi API overview technote Wi-Fi Aware framework documentation WirelessInsights framework documentation iOS Network Signal Strength forums post Network Extension Resources Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). WWDC 2017 Session 701 Your Apps and Evolving Network Security Standards [1] — This is generally interesting, but the section starting at 17:40 is, AFAIK, the best information from Apple about how certificate revocation works on modern systems. Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] This video is no longer available from Apple, but the URL should help you locate other sources of this info.

I'm encountering a null pointer dereference crash pointing to the internals of CFNetwork library code on iOS. I'm spawning URLSessionTasks at a decently fast rate (~1-5 per second), with the goal being to generate application layer network traffic. I can reliably encounter this crash pointing to NetConnection::dequeue right after a new task has been spawned and had the resume method called. I suspect that this is perhaps a race condition or some delegate/session object lifecycle bug. The crash appears to be more easily reproduced with a higher rate of spawning URLSessionTasks. I've included the JSON crash file, the lldb stack trace, and the source code of my URLSession(Task) usage. urlsession_stuff_stacktrace.txt urlsession_stuff_source.txt urlsession_crash_report.txt

We are developing a watchOS application that records long audio sessions and uploads them to our backend in chunks (~5 MB each) using pre-signed URLs and URLSession background upload. Current behavior: While audio recording is active, uploads continue successfully even when the app is in the background. Once the recording stops, if multiple chunks (e.g., 10+) are still pending, the remaining uploads do not proceed in the background and appear to be suspended. We attempted to use WKExtendedRuntimeSession (mindfulness type) to allow sufficient time to enqueue background upload tasks, but the session is invalidated when the app goes to the background (e.g., wrist down or app inactive), which prevents reliable scheduling of uploads. Additionally, we added the entitlement: com.apple.developer.extended-runtime-session (mindfulness) in the Watch app entitlements file, but Xcode automatic signing fails with: “Provisioning profile does not include the com.apple.developer.extended-runtime-session entitlement.” It appears that the provisioning profile is not being updated to include this entitlement. Our questions: Is WKExtendedRuntimeSession (mindfulness) expected to support scheduling background URLSession uploads after the app goes to background? How should we reliably complete pending background uploads on watchOS after a long recording session ends? Is there any additional entitlement or recommended approach for this use case? Why is the extended runtime entitlement not being applied to the provisioning profile despite being added in the entitlements file? We are aiming to follow Apple-recommended practices for long-running tasks and background uploads on watchOS. Any guidance would be greatly appreciated.

com.apple.main-thread 0 StarMaker 0x5c40854 _isPlatformVersionAtLeast.cold.2 + 4425680980 1 StarMaker 0x526d278 -[FPRScreenTraceTracker displayLinkStep] + 191 (FPRScreenTraceTracker.m:191) 2 QuartzCore 0xbe924 CA::Display::DisplayLinkItem::dispatch(CA::SignPost::Interval<(CA::SignPost::CAEventCode)835322056>&) + 64 3 QuartzCore 0x9bf38 CA::Display::DisplayLink::dispatch_items(unsigned long long, unsigned long long, unsigned long long) + 880 4 QuartzCore 0xaf770 CA::Display::DisplayLink::dispatch_deferred_display_links(unsigned int) + 360 5 UIKitCore 0x7dee4 _UIUpdateSequenceRunNext + 128 6 UIKitCore 0x7d374 schedulerStepScheduledMainSectionContinue + 60 7 UpdateCycle 0x1560 UC::DriverCore::continueProcessing() + 84 8 CoreFoundation 0x164cc __CFMachPortPerform + 168 9 CoreFoundation 0x460b0 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION + 60 10 CoreFoundation 0x45fd8 __CFRunLoopDoSource1 + 508 11 CoreFoundation 0x1dc1c __CFRunLoopRun + 2168 12 CoreFoundation 0x1ca6c _CFRunLoopRunSpecificWithOptions + 532 13 GraphicsServices 0x1498 GSEventRunModal + 120 14 UIKitCore 0x9ddf8 -[UIApplication _run] + 792 15 UIKitCore 0x46e54 UIApplicationMain + 336 16 StarMaker 0x50c965c main + 18 (main.m:18) 17 ??? 0x19a9dae28 (缺少) Thread 0 libsystem_kernel.dylib 0x67f4 __semwait_signal + 8 1 libsystem_c.dylib 0xc7e4 nanosleep + 220 2 ZorroRtcEngineKit 0x1eb0f8 std::__Cr::this_thread::sleep_for(std::__Cr::chrono::duration<long long, std::__Cr::ratio<1l, 1000000000l>> const&) + 198 (pthread.h:198) 3 ZorroRtcEngineKit 0x27d30 zorro::KbLog::Loop() + 88 (kblog.cc:88) 4 ZorroRtcEngineKit 0x286e8 <deduplicated_symbol> + 4667967208 5 libsystem_pthread.dylib 0x444c _pthread_start + 136 6 libsystem_pthread.dylib 0x8cc thread_start + 8 Thread 0 libsystem_kernel.dylib 0x67f4 __semwait_signal + 8 1 libsystem_c.dylib 0xc7e4 nanosleep + 220 2 ZorroRtcEngineKit 0x1eb0f8 std::__Cr::this_thread::sleep_for(std::__Cr::chrono::duration<long long, std::__Cr::ratio<1l, 1000000000l>> const&) + 198 (pthread.h:198) 3 ZorroRtcEngineKit 0x19a4e4 zorro::ZkbLog::Loop() + 157 (zlog.cc:157) 4 ZorroRtcEngineKit 0x286e8 <deduplicated_symbol> + 4667967208 5 libsystem_pthread.dylib 0x444c _pthread_start + 136 6 libsystem_pthread.dylib 0x8cc thread_start + 8 Thread 0 libsystem_kernel.dylib 0x67f4 __semwait_signal + 8 1 libsystem_c.dylib 0xc7e4 nanosleep + 220 2 ZorroRtcEngineKit 0x1eb0f8 std::__Cr::this_thread::sleep_for(std::__Cr::chrono::duration<long long, std::__Cr::ratio<1l, 1000000000l>> const&) + 198 (pthread.h:198) 3 ZorroRtcEngineKit 0x19c4d8 zorro::QosManager::Loop() + 966 (string:966) 4 ZorroRtcEngineKit 0x286e8 <deduplicated_symbol> + 4667967208 5 libsystem_pthread.dylib 0x444c _pthread_start + 136 6 libsystem_pthread.dylib 0x8cc thread_start + 8

I am referencing: https://developer.apple.com/documentation/foundation/pausing-and-resuming-uploads Specifically: You can’t resume all uploads. The server must support the latest resumable upload protocol draft from the HTTP Working Group at the IETF. Also, uploads that use a background configuration handle resumption automatically, so manual resuming is only needed for non-background uploads. I have control over both the app and the server, and can't seem to get it to work automatically with a background url session. In other words, making multiple requests to get the offset then upload, easy but I am trying to leverage this background configuration resume OS magic. So anyone know what spec version does the server/client need to implement? The docs reference version 3, however the standard is now at like 11. Of course, I am trying out 3. Does anyone know how exactly this resume is implemented in iOS, and what exactly it takes care of? I assumed that I can just POST to a generic end point, say /files, then the OS receives a 104 Location, and saves that. If the upload is interrupted, when the OS resumes the upload, it has enough information to figure out how to resume from the exact offset, either by making a HEAD request to get the offset, or handle a 409. I am assuming it does this, as if it doesn't, the 'uploads that use a background configuration handle resumption automatically' is useless, if it just restarts from 0. Note, of course making individual POST/HEAD/PATCH requests manually works, but at that point I'm not really leveraging any OS auto-magic, and am just consuming an API that could really implement any spec. This won't work in the background, as the OS seems to disallow random HTTP requests when it wakes the app for URLSession background resumes. As of right now, I have it 'partially' working, insofar as the app does receive the 104 didReceiveInformationalResponse url delegate call, however it seems to then hang; it stops sending bytes, seemingly when the 104 is received. However, the request does not complete. In other words, it doesn't seem to receive a client timeout or otherwise indicate the request has finished. Right now, I am starting a single request, POSTing to a /files end point, i.e. I am not getting the location first, then PATCHing to that, as if I do that, the OS 'automatic' resuming fails with a 409, i.e. it doesn't seem to make a HEAD request and/or use the 409 offset correction then continue with the PATCH. Any idea what could be going on?

We are currently experiencing an issue that occurs only on iPhone 17 models. In our app, after connecting to an external device, users can download multiple video files stored on the device. When downloading several videos consecutively, the device consistently stops receiving responses midway through the process. As a result, no response is returned, and the connection between the app and the device is eventually lost. This issue does not occur on any iPhone models prior to iPhone 17. It is reproducible across all iPhone 17 devices within our company. This is a critical issue, and we need urgent assistance. The main error logs show two patterns: • Connection loss • Timeout At the OS level, the only error codes we receive are: • -1005 (Network connection lost) • -1001 (Request timed out) Unfortunately, we are unable to obtain more detailed error information beyond these codes, which makes further debugging difficult. We have attached the relevant logs below. We would greatly appreciate any guidance on how to further investigate or resolve this issue. 310.0 / :: 81 % ::: 251.21481481481482 310.0 / :: 82 % ::: 254.23280423280423 310.0 / :: 83 % ::: 257.3820105820106 310.0 / :: 84 % ::: 260.4 KeepAlive SEND id=423F1336-6239-4B3B-9414-5A987D85D564 at=2026-02-24T12:56:43Z timeout=60.000000s current: D20-Q2-PLUS, ssid: D20-Q2-PLUS_136a63 KeepAlive SKIP (in-flight) tcp_output [C10.1.1:3] flags=[R.] seq=4017430266, ack=4146413113, win=2048 state=CLOSED rcv_nxt=4146413113, snd_una=4017429847 nw_read_request_report [C10] Receive failed with error "Operation timed out" nw_flow_add_write_request [C10 192.168.000.0:443 failed parent-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, dns, uses wifi, LQM: good)] cannot accept write requests nw_write_request_report [C10] Send failed with error "Socket is not connected" Task <5BDBE621-329A-45E9-B236-9C173E92A41F>.<7> HTTP load failed, 361/0 bytes (error code: -1005 [4:-4]) Task <5BDBE621-329A-45E9-B236-9C173E92A41F>.<7> finished with error [-1005] Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x13e632160 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x14cfe5a90 [0x201746068]>{length = 16, capacity = 16, bytes = 0x100201bbc0a86f010000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <5BDBE621-329A-45E9-B236-9C173E92A41F>.<7>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <5BDBE621-329A-45E9-B236-9C173E92A41F>.<7>" ), NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https://192.168.000.0/keepalive, NSErrorFailingURLKey=https://192.168.000.0/keepalive, _kCFStreamErrorDomainKey=4} KeepAlive FAIL id=423F1336-6239-4B3B-9414-5A987D85D564 elapsed=29.203s status=-1 error=Optional(Alamofire.AFError.sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x13e632160 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x14cfe5a90 [0x201746068]>{length = 16, capacity = 16, bytes = 0x100201bbc0a86f010000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, ), NSLocalizedDescription=The network connection was lost., KeepAlive FAIL 1001 Log KeepAlive SEND id=FC433405-C1F7-47EF-AF9E-D12E67B071FA at=2026-02-24T12:22:38Z timeout=60.000000s current: D20-Q2-PLUS, ssid: VUEROID_D20-Q2-PLUS_136a63 KeepAlive FAIL id=FC433405-C1F7-47EF-AF9E-D12E67B071FA elapsed=7.834s status=-1 error=Optional(Alamofire.AFError.sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo={_kCFStreamErrorCodeKey=60, NSUnderlyingError=0x135e612f0 {Error Domain=kCFErrorDomainCFNetwork Code=-1001 "(null)" UserInfo={_NSURLErrorNWPathKey=satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, dns, uses wifi, LQM: good, _kCFStreamErrorCodeKey=60, _kCFStreamErrorDomainKey=1}}, ), NSLocalizedDescription=The request timed out., NSErrorFailingURLKey=https://192.168.000.0/keepalive, _kCFStreamErrorDomainKey=1})) KeepAlive FAIL ignored count=1 error=Server error : Optional(Alamofire.AFError.sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo={_kCFStreamErrorCodeKey=60, KeepAlive SEND id=A64AE4C0-28B4-41E3-AAC9-422C41D99D15 at=2026-02-24T12:22:58Z timeout=60.000000s KeepAlive FAIL id=110B96DA-4D88-45E0-B8F7-D0A9798593AE elapsed=43.605s status=-1 error=Optional(Alamofire.AFError.sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x135e60f60 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x144dfee40 [0x201746068]>{length = 16, capacity = 16, bytes = 0x100201bbc0a86f010000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, ), NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https://192.168.000.0/keepalive, NSErrorFailingURLKey=https://192.168.000.0/keepalive, _kCFStreamErrorDomainKey=4})) KeepAlive FAIL ignored count=2 error=Server error : Optional(Alamofire.AFError.sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={_kCFStreamErrorCodeKey=-4, NSUnderlyingError=0x135e60f60 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x144dfee40 [0x201746068]>{length = 16, capacity = 16, bytes = 0x100201bbc0a86f010000000000000000}, _kCFStreamErrorCodeKey=-4, _kCFStreamErrorDomainKey=4}}, Network type changed, hasWiFiInterface :false We are sending a keepalive request every 30 seconds to maintain the connection state with the device. Most of the issues occur during this keepalive process, and this is when the logs mentioned earlier are generated. Based on our debugging so far, the keepalive function itself is being called as expected. However, the execution appears to stall while waiting for a response from the device. After remaining in that state for some time, the session eventually ends with either a timeout or a connection loss error. We are use almofire 4.0.1. According to the firmware developer, when this issue occurs, there are no corresponding values or logs received on the device side. Therefore, we are currently investigating whether this might be related to a networking issue on the iPhone side. All other features are functioning normally. The problem occurs only when downloading VOD video files, and the reproduction rate is 100% under that condition.

Hi Team, Looking for an answer, if it's just us or a widespread issue. Since Sept, our clients Apple devices can't load a Captive Portal on Apple devices. Client wants the CNA to pop up and I can't get it to happen! Android and Windows devices all work correctly with their respective popups, but CNA will not work. No changes done on our side and after multiple tshoots and getting vendors to take multiple PCAPs found, Apple devices are not initiating a HTTP GET request as per Meraki >> https://documentation.meraki.com/MR/MR_Splash_Page/Splash_Page_Traffic_Flow_and_Troubleshooting The work around is to force a HTTP GET request by manually going into the browser and initiate a http site (we tried 1.1.1.1, also tried other public HTTP sites and it works) and that redirects to our Captive Portal page.

As part of iOS 26, we get X25519MLKEM768 key exchange group support, but SecP256r1MLKEM768 and SecP384r1MLKEM1024 are not supported. Is there any way to enable these key exchange groups on iOS 26? We need them for WKWebView and NSURLSession. STEPS TO REPRODUCE On iOS 26, connect to the PQC server using Safari. The key exchange group is limited to X25519MLKEM768.

I've implemented func urlSession(_ session: URLSession, task: URLSessionTask, willPerformHTTPRedirection response: HTTPURLResponse, newRequest request: URLRequest, completionHandler: @escaping (URLRequest?) -> Void) and func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) I've put a breakpoint in each but the BP in willPerformHTTPRedirection never fires. When the didWriteData fires and I inspect downloadTask.originalRequest I see my original request URL When I inspect downloadTask.currentRequest the returned request contains a different URL. I'm the farthest thing from an HTTP wizard, but I had thought when originalRequest differs from currentRequest there had been some sort of server-side 'redirection'. Is there a way for my code to receive a callback when something like this happens? NOTE: my download code works fine, I'm just hoping to detect the case when currentRequest changes. any/all guidance greatly appreciated on the off chance it helps, are are my original and current request values: (lldb) po downloadTask.originalRequest ▿ Optional<URLRequest> ▿ some : https://audio.listennotes.com/e/p/c524803c1a90412f922948274ecc3625/ (lldb) po downloadTask.currentRequest ▿ Optional<URLRequest> ▿ some : https://26973.mc.tritondigital.com:443/OMNY_HAPPIERWITHGRETCHENRUBIN_PODCAST_P/media-session/76cfceb2-1801-4570-b830-ded57611a9cf/d/clips/796469f9-ea34-46a2-8776-ad0f015d6beb/e1b22d0b-6974-4bb8-81ba-b2480119983c/2f35a8ca-b982-44e9-8122-b3dc000ae0e1/audio/direct/t1769587393/Ep_571_Want_to_Join_Us_for_a_No-Spend_February_Plus_a_Better_Word_for_Squats.mp3?t=1769587393&in_playlist=751ada7f-ded3-44b9-bfb8-b2480119985b&utm_source=Podcast

I have an app that has been using the following code to down load audio files: if let url = URL(string: episode.fetchPath()) { var request = URLRequest(url: url) request.httpMethod = "get" let task = session.downloadTask(with: request) And then the following completionHandler code: func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) { try FileManager.default.moveItem(at: location, to: localUrl) In the spirit of modernization, I'm trying to update this code to use async await: var request = URLRequest(url: url) request.httpMethod = "get" let (data, response) = try await URLSession.shared.data(for: request) try data.write(to: localUrl, options: [.atomicWrite, .completeFileProtection]) Both these code paths use the same url value. Both return the same Data blobs (they return the same hash value) Unfortunately the second code path (using await) introduces a problem. When the audio is playing and the iPhone goes to sleep, after 15 seconds, the audio stops. This problem does not occur when running the first code (using the didFinish completion handler) Same data, stored in the same URL, but using different URLSession calls. I would like to use async/await and not have to experience the audio ending after just 15 seconds of the device screen being asleep. any guidance greatly appreciated.

Is there any way to forcibly disable using QUIC? I've noticed this ends up causing issues with our ISP / router, and noticed for many of our customers as well. Creating an ephemeral session doesn't change things, and setting the request to "assumeHttp3Capable" to false doesn't fix things either. We are using Cloudflare Workers as the URL we are hitting, and thus aren't able to disable this server-side.

iOS BGProcessingTask + Background Upload Not Executing Reliably on TestFlight (Works in Debug) Description: We are facing an issue with BGTaskScheduler and BGProcessingTask when trying to perform a background audio-upload flow on iOS. The behavior is inconsistent between Debug builds and TestFlight (Release) builds. Summary of the Problem Our application records long audio files (up to 1 hour) and triggers a background upload using: BGTaskScheduler BGProcessingTaskRequest Background URLSession (background with identifier) URLSession background upload task + AppDelegate.handleEventsForBackgroundURLSession In Debug mode (Xcode → Run on device), everything works as expected: BGProcessingTask executes handleEventsForBackgroundURLSession fires Background URLSession continues uploads reliably Long audio files successfully upload even when the app is in background or terminated However, in TestFlight / Release mode, the system does not reliably launch the BGProcessingTask or Background URLSession events. Technical Details We explicitly register BGTaskScheduler: BGTaskScheduler.shared.register( forTaskWithIdentifier: "example.background.process", using: nil ) { task in self.handleBackgroundProcessing(task: task as! BGProcessingTask) } We schedule it using: let request = BGProcessingTaskRequest(identifier: "example.background.process") request.requiresNetworkConnectivity = true request.requiresExternalPower = false try BGTaskScheduler.shared.submit(request) We also use Background URLSession: let config = URLSessionConfiguration.background(withIdentifier: sessionId) config.sessionSendsLaunchEvents = true config.isDiscretionary = false AppDelegate.handleEventsForBackgroundURLSession is implemented correctly and works in Debug. Issue Observed (TestFlight Only) In TestFlight builds: BGProcessingTask rarely triggers, or the system marks it as NO LONGER RUNNING. Background upload tasks sometimes never start or complete. No logs appear from our BGProcessingTask handler. system logs show messages like: NO LONGER RUNNING bgProcessing-example.background.process Tasks running in group [com.apple.dasd.defaultNetwork] are 1! This occurs most frequently for large audio uploads (30–60 minutes), while small files behave normally. What We Have Verified Proper Info.plist values: Permitted background modes: processing, audio, fetch BGTaskSchedulerPermittedIdentifiers contains our identifier BGProcessingTask is being submitted successfully (no errors) App has microphone permission + background audio works Device plugged/unplugged doesn’t change outcome Key Question for Apple We need clarification on: Why BGProcessingTask behave differently between Debug and TestFlight builds? Are there additional restrictions or heuristics (related to file size, CPU usage, runtime, network load, or power constraints) that cause BGProcessingTask to be throttled or skipped in Release/TestFlight? How can we guarantee a background upload continues reliably for large files (100MB–500MB) on TestFlight and App Store builds? Is there an Apple-recommended pattern to combine BGProcessingTask + Background URLSession for long-running uploads? Expected Result Background uploads should continue reliably for long audio files (>30 minutes) when the app goes to background or is terminated, in the same way they currently function in Debug builds.

Hi, I'm experiencing intermittent delays with URLSession where requests take 3-4 seconds to be sent, even though the actual server processing is fast. This happens randomly, maybe 10-20% of requests. The pattern I've noticed is I create my request I send off my request using try await urlSession.data(for: request) My middleware ends up receiving this request 4-7s after its been fired from the client-side The round trip ends up taking 4-7s! This hasn't been reproducible consistently at all on my end. I've also tried ephemeral URLSessions (so recreating the session instead of using .shared so no dead connections, but this doesn't seem to help at all) Completely lost on what to do. Please help!

I have an Xcode app where currently txt files in the project display text data as a list. I can search through the lists and have buttons that will swap between different lists of information that you can look through. The next task is I have URL connections to docx files on a SharePoint site. I am trying to use an URLsession function to connect to the URL links to download the documents to the document directory then have the application read the doc information to then be displayed as the txt info would. The idea is that the docx files are a type of online update version of the data. So when the app is used and on wifi, the app can update the list data with the docx files. I have code set up that should access the URL files but I am struggling to figure out how to read the data and access from this Documents directory. I have been looking online and so far I am at a loss on where to go here. If anyone can help or provide some insight I would greatly appreciate it. I can try and provide code samples to help explain things if that is needed.

Hi everyone, I’ve run into a consistent issue on multiple Apple Vision Pro devices where downloads using URLSessionConfiguration.background are between 4× and 10x slower than when using URLSessionConfiguration.default. This issue is systematic and can easily be reproduced. This only happens on device, in the simulator, both configurations download files at the expected speed with respect to the network speed. Details: Tested on visionOS 26.0.1 and 26.1 (public releases) Reproduced across 2 Vision Pro (currently testing on a third one) Reproduced on 2 different Wi-fi networks (50mb/s and 880mb/s) From my tests this speed issue seems to affects multiple apps on my device: Stobo Vision (our app), Immersive India, Amplium Not server-related (reproduces with Apple CDN, S3, and DigitalOcean) I’ve built a small sample project that makes this easy to reproduce, it downloads a large file (1.1 GB video) using two managers: One with URLSessionConfiguration.default One with URLSessionConfiguration.background You can also try it with your own file url (from an s3 for example) Expected behavior: Background sessions should behave similarly to default sessions in terms of throughput, just as they do in the simulator. To be clear I am comparing both config when running in the foreground, not in the background. Actual behavior: Background sessions on Vision Pro are significantly slower, making them less usable for large file downloads. On this screenshot it's even reaching 27x slower than the expected speed. Default config takes ~97s to download and Background config takes ~2640s. I do now have the fastest internet connection but 44min to download 90.5MB is extremely slow. Has anyone else seen this behavior or found a workaround? Or is this an expected behavior from URLSessionConfiguration.background? If I'm doing something wrong please let me know Repo link: https://github.com/stobo-app/DownloadConfigTesting

Getting -10985 error from urlSession while attempting to make a connection. Not sure why this is happening if anyone is aware please help

I'm trying to implement support for grpc http/2 streams using NSURLSession. Almost everything works fine, data streaming is flowing from the server and from the client and responses are coming through my NSURLSessionTaskDelegate. I'm getting the responses and streamed data through the appropriate handlers (didReceiveData, didReceiveResponse). However, I cannot seem to find an API to access the trailers expected by grpc. Specifically, the expected trailer "grpc-status: 0" is in the response, but after the data. Is there no way to gain access to trailers in the NSURLSession Framework?

Title / Summary Crash in libquic.dylib when app is backgrounded and issues an HTTP/3 request Description On iOS 26, the app crashes inside libquic.dylib while performing a network request using HTTP/3 (QUIC) after the app has moved to the background. The crash happens within low-level QUIC / libquic internals. Reproduction Steps Launch the app, perform normal operations. Background the app (press home / switch away). While in background, trigger a network request that uses HTTP/3 / QUIC. Observe that the app crashes (stack trace pointing into libquic.dylib). Expected Behavior The HTTP/3 request in background should either be handled gracefully (fail or complete) without causing a crash; the app must not be terminated due to internal libquic failures. Actual Behavior The app crashes with signals/exceptions coming from libquic.dylib (in the QUIC / packet building / encryption / key state logic) when a HTTP/3 request is made in background. Environment / Device Information • OS: iOS 26 • Device: iPhone 13 Pro Max • Network environment: (Wi-Fi / Cellular) • HTTP/3 support: enabled in URLSession / Network framework Stack Trace： 8eedc0df3d914b0faf8def9af3b21574-symbolicated.crash

Hello Apple Support Team, We are experiencing a performance issue with HTTP/3 in our iOS application during testing. Problem Description: Network requests using HTTP/3 are significantly slower than expected. This issue occurs on both Wi-Fi and 4G networks, with both IPv4 and IPv6. The same setup worked correctly in an earlier experiment. Key Observations: The slowdown disappears when the device uses: · A personal hotspot. · Network Link Conditioner (with no limitations applied). · Internet sharing from a MacBook via USB (where traffic was also inspected with Wireshark without issues). The problem is specific to HTTP/3 and does not occur with HTTP/2. The issue is reproducible on iOS 15, 18.7, and the latest iOS 26 beta. HTTP/3 is confirmed to be active (via assumeHttp3Capable and Alt-Svc header). Crucially, the same backend endpoint works with normal performance on Android devices and using curl with HTTP/3 support from the same network. I've checked the CFNetwork logs in the Console but haven't found any suspicious errors or obvious clues that explain the slowdown. We are using a standard URLSession with basic configuration. Attempted to collect qlog diagnostics by setting the QUIC_LOG_DIRECTORY=~/ tmp environment variable, but the logs were not generated. Question: What could cause HTTP/3 performance to improve only when the device is connected through a hotspot, unrestricted Network Link Conditioner, or USB-tethered connection? The fact that Android and curl work correctly points to an issue specific to the iOS network stack. Are there known conditions or policies (e.g., related to network interface handling, QoS, or specific packet processing) that could lead to this behavior? Additionally, why might the qlog environment variable fail to produce logs, and are there other ways to obtain detailed HTTP/3 diagnostic information from iOS? Any guidance on further diagnostic steps or specific system logs to examine would be greatly appreciated. Thank you for your assistance.

Upgrade iOS to 18.5, then install app in Xcode and grant permissions to send UDP but it won't work. Then restart device, open this installed app and send UDP again and this time it becomes OK. Repeat these steps and it all goes well. The UDP pod I use in app is CocoaAsyncSocket. The same thing happens on iPhone 14 Plus and 16 Pro, both iOS 18.5. How to explain this phenomenon, thanks for your help in advance.

I’m stuck with repeated production crashes in my SwiftUI app and I can’t make sense of the traces on my own. The symbolicated reports show the same pattern: Crash on com.apple.CFNetwork.LoaderQ with EXC_BAD_ACCESS / PAC failure Always deep in CFNetwork, most often in URLConnectionLoader::loadWithWhatToDo(NSURLRequest*, _CFCachedURLResponse const*, long, URLConnectionLoader::WhatToDo) No frames from my code, no sign of AuthManager or tokens. What I’ve tried: Enabled Address Sanitizer, Malloc Scribble, Guard Malloc, Zombies. Set CFNETWORK_DIAGNOSTICS=3 and collected Console logs. Stress-tested the app (rapid typing, filter switching, background/foreground, poor network with Network Link Conditioner). Could not reproduce the crash locally. So far: Logs show unrelated performance faults (I/O on main thread, CLLocationManager delegate), but no obvious CFNetwork misuse. My suspicion is a URLSession lifetime or delegate/auth-challenge race, but I can’t confirm because I can’t trigger it. Since starting this investigation, I also refactored some of my singletons into @State/@ObservedObject dependencies. For example, my app root now wires up AuthManager, BackendService, and AccountManager (where API calls happen using async/await) as @State properties: @State var authManager: AuthManager @State var accountManager: AccountManager @State var backendService: BackendService init() { let authManager = AuthManager() self._authManager = .init(wrappedValue: authManager) let backendService = BackendService(authManager: authManager) self._backendService = .init(wrappedValue: backendService) self._accountManager = .init(wrappedValue: AccountManager(backendService: backendService)) } I don’t know if this refactor is related to the crash, but I am including it to be complete. Apologies that I don’t have a minimized sample project — this issue seems app-wide, and all I have are the crash logs. Request: Given the crash location (URLConnectionLoader::loadWithWhatToDo), can Apple provide guidance on known scenarios or misuses that can lead to this crash? Is there a way to get more actionable diagnostics from CFNetwork beyond CFNETWORK_DIAGNOSTICS to pinpoint whether it’s session lifetime, cached response corruption, or auth/redirect? Can you also confirm whether my dependency setup above could contribute to URLSession or backend lifetime issues? I can’t reliably reproduce the crash, and without Apple’s insight the stack trace is effectively opaque to me. Thanks for your time and help. Happy to send multiple symbolicated crash logs at request. Thanks for any help. PS. Including 2 of many similar crash logs. Can provide more if needed. Atlans-2025-07-29-154915_symbolicated (cfloader).txt Atlans-2025-08-08-124226_symbolicated (cfloader).txt