Hello, I'm working on a Transparent Proxy and when the proxy is being stopped, I'm stopping all the flows by calling flow.closeWriteWithError(POSIXError(.ECANCELED)) flow.closeReadWithError(POSIXError(.ECANCELED)) Then all the flows are deallocated. When deallocating the flow the crash occurs: OS Version: macOS 14.1.2 (23B92) Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000001, 0x000000018c2ef704 Termination Reason: Namespace SIGNAL, Code 5 Trace/BPT trap: 5 Terminating Process: exc handler [553] Thread 32 Crashed:: Dispatch queue: <my dispatch queue> 0 CoreFoundation 0x18c2ef704 CF_IS_OBJC + 76 1 CoreFoundation 0x18c23f61c CFErrorGetDomain + 32 2 libnetworkextension.dylib 0x19fe56a00 flow_error_to_errno + 28 3 libnetworkextension.dylib 0x19fe56920 flow_handle_pending_write_requests + 216 4 libnetworkextension.dylib 0x19fe5667c __NEFlowDeallocate + 380 5 CoreFoundation 0x18c2efe28 _CFRelease + 292 6 NetworkExtension 0x19d208390 -[NEAppProxyFlow dealloc] + 36 Is there any way to debug what is happening and if it's related to closing the flow with POSIXError? Thank you

I have checked the storage space of my phone. There is still over a hundred gigabytes of space left. An error occurred when the app was checking the network interface status. The error message is as follows:Error : Error Domain=NSPOSIXErrorDomain Code=28 "No space left on device" UserInfo={_NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <7DB1CBFD-B9BE-422D-9C9A-78D8FC04DC1B>.<76>, _kCFStreamErrorDomainKey=1, _kCFStreamErrorCodeKey=28, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <7DB1CBFD-B9BE-422D-9C9A-78D8FC04DC1B>.<76>" ), _NSURLErrorNWPathKey=satisfied (Path is satisfied), interface: pdp_ip0[lte], ipv4, ipv6, dns, expensive, estimated upload: 65536Bps, uses cell}

When running my app with Xcode16.4, it crashed with the error: dyld[1045]: Symbol not found: ___res_9_state Referenced from: <8B329554-5BEF-38D0-BFCD-1731FA6120CB> /private/var/containers/Bundle/Application/00C941BA-E397-4D0B-B280-E75583FF2890/***.app/***.debug.dylib Expected in: <7D74C679-8F55-3A01-9AA2-C205A4A19D3E> /usr/lib/libresolv.9.dylib The ___res_9_state related code in my app is: let state = __res_9_state() res_9_ninit(state) var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: Int(MAXNS)) let found = Int(res_9_getservers(state, &servers, Int32(MAXNS))) res_9_nclose(state) if found > 0 { return Array(servers[0..<found]).filter() { $0.sin.sin_len > 0 } } else { return [] } Previously, __res_9_state() could run normally in Xcode 16.1 How to fix this problem?

I want to create a NAT64/DNS64 test network as shown here, but I cannot figure out how to do it in the latest versions of MacOS. Is this still available and how can I access the "Create NAT64 Network" checkbox?

This happens when trying to connect to my development web server. The app works fine when connecting to my production server. The production server has a certificate purchased from a CA. My development web server has a locally generated certificate (from mkcert). I have dragged and dropped the rootCA.pem onto the Simulator, although it doesn't indicate it has been loaded the certificate does appear in the Settings app and is checked to be trusted. I have enabled "App Sandbox" and "Outgoing connections (Client)". I have tested the URL from my local browser which is working fine. What am I missing?

Problem : Connection error occurs in iOS26 beta while connecting to the device's softap via commercial app (Socket exception errSSLfeerBadCert CFSreamErrorDomainSSL code -9825). iOS 18 release version does not occur. Why does it cause problems? Does the iOS 26 version not cause problems? Is there a way to set it up in the app so that the iOS 26 beta doesn't cause problems? error : "alias":"SOCKET_LOG", "additional":{"currentNetworkStatus":"socket e=errSSLPeerBadCert ns WifiStatus: Connected Error Domain kCFStreamErrorDomainSSL Code-9825 "(null)" UserInfo={NSLocalizedRecoverySuggestion=Error code definition can be found in Apple's SecureTransport.h} Description : It's an issue that happens when you connect our already mass-produced apps to our home appliances (using SoftAP), and it's currently only happening in iOS 26 beta. This particular issue didn't appear until iOS 18 version. Let me know to make sure that this issue will persist with the official release of iOS 26? If the issue continues to occur with the official version, would you share any suggestions on how to mitigate or avoid it. Also, it would be helpful to find out if there are known solutions or processes such as exemptions to fix this issue.

Hi! My project has the Local Push Connectivity entitlement for a feature we have requiring us to send low-latency critical notifications over a local, private Wi-Fi network. We have our NEAppPushProvider creating a SSE connection using the Network framework with our hardware running a server. The server sends a keep-alive message every second. On an iPhone 16 with iOS 18+, the connection is reliable and remains stable for hours, regardless of whether the iOS app is in the foreground, background, or killed. One of our QA engineers has been testing on an iPhone 13 running iOS 16, and has notice shortly after locking the phone, specifically when not connected to power the device seems to turn off the Wi-Fi radio. So when the server sends a notification, it is not received. About 30s later, it seems to be back on. This happens on regular intervals. When looking at our log data, the provider does seem to be getting stopped, then restarted shortly after. The reason code is NEProviderStopReasonNoNetworkAvailable, which further validates that the network is getting dropped by the device in regular intervals. My questions are: Were there possibly silent changes to the framework between iOS versions that could be the reason we're seeing inconsistent behavior? Is there a connection type we could use, instead of SSE, that would prevent the device from disconnecting and reconnecting to the Wi-Fi network? Is there an alternative approach to allow us to maintain a persistent network connection with the extension or app?

I'm creating a simple p2p server to advertise a service: // server let txtRecord = NWTXTRecord(["key": "value"]) NWListener.Service(name: name, type: "_p2p._tcp", domain: nil, txtRecord: txtRecord) and client to look that service up: // client switch result.endpoint { case let .service(name: name, type: type, domain: domain, interface: interface): print(result.metadata) The client is getting the advertisement ok, but metadata is nil. I expected to see a txt record there, is that not supported? public let metadata: NWBrowser.Result.Metadata /// Additional metadata provided to the browser by a service. Currently, /// only Bonjour TXT records are supported. Is the above server making a Bonjour TXT record or something else? Basically what I want is to pass a short key/value data as part of advertisement.

Hi, Our project is a MacOS SwiftUI GUI application that bundles a (Sandboxed) System Network Extension, signed with a Developer ID certificate for distribution outside of the app store. The system network extension is used to write a packet tunnel provider (NEPacketTunnelProvider), as our project requires the creation of a TUN device. In order for our System VPN to function, it must reach out to a (self-hosted) server (i.e. to discover a list of peers). Being self-hosted, this server is typically not accessible via the public web, and may only be accessible from within a VPN (such as those also implemented using NEPacketTunnelProvider, e.g. Tailscale, Cloudflare WARP). What we've discovered is that the networking code of the System Network Extension process does not attempt to use the other VPN network interfaces (utunX) on the system. In practice, this means requests to IPs and hostnames that should be routed to those interfaces time out. Identical requests made outside of the Network System Extension process use those interfaces and succeed. The simplest example is where we create a URLSession.downloadTask for a resource on the server. A more complicated example is where we execute a Go .dylib that continues to communicate with that server. Both types of requests time out. Two noteworthy logs appear when packets fail to send, both from the kernel 'process': cfil_hash_entry_log:6088 <CFIL: Error: sosend_reinject() failed>: [30685 com.coder.Coder-Desktop.VPN] <UDP(17) out so b795d11aca7c26bf 57728068503033955 57728068503033955 age 0> lport 3001 fport 3001 laddr 100.108.7.40 faddr 100.112.177.88 hash 58B15863 cfil_service_inject_queue:4472 CFIL: sosend() failed 49 I also wrote some test code that probes using a UDP NWConnection and NWPath availableInterfaces. When run from the GUI App, multiple interfaces are returned, including the one that routes the address, utun5. When ran from within the sysex, only en0 is returned. I understand routing a VPN through another is unconventional, but we unfortunately do need this functionality one way or another. Is there any way to modify which interfaces are exposed to the sysex? Additionally, are these limitations of networking within a Network System Extension documented anywhere? Do you have any ideas why this specific limitation might exist?

Hi everyone, I’m currently experimenting with building a simple DNS filter using Apple’s Packet Tunnel framework. Here’s the flow I’m trying to implement: Create a TUN interface Set up a UDP socket Read packets via packetFlow.readPackets Parse the raw IP packet Forward the UDP payload through the socket Receive the response from the server Reconstruct the IP packet with the response Write it back to the TUN interface using packetFlow.writePackets Here’s an example of an intercepted IP packet (DNS request): 45 00 00 3c 15 c4 00 00 40 11 93 d1 c0 a8 00 64 08 08 08 08 ed 6e 00 35 00 28 e5 c9 7f da 01 00 00 01 00 00 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 And here’s the IP packet I tried writing back into the TUN interface (DNS response): 45 00 00 89 5e 37 40 00 40 11 0b 11 08 08 08 08 c0 a8 00 64 00 35 ed 6e 00 75 91 e8 7f da 81 80 00 01 00 04 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 c0 0c 00 05 00 01 00 00 0c fb 00 11 04 74 69 6d 65 01 67 07 61 61 70 6c 69 6d 67 c0 17 c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 fd c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 7d c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 54 fb Unfortunately, it seems the packet is not being written back correctly to the TUN interface. I’m not seeing any expected DNS response behavior on the device. Also, I noticed that after creating the TUN, the interface address shows up as 0.0.0.0:0 in Xcode. The system log includes this message when connecting the VPN: NWPath does not have valid interface: satisfied (Path is satisfied), interface: utun20[endc_sub6], ipv4, dns, expensive, uses cellular Does anyone know how to properly initialize the TUN so that the system recognizes it with a valid IP configuration? Or why my written-back packet might be getting ignored? Any help would be appreciated!

Our application has initiated an NSURLSession data task, and we have received an initiation ID. However, Application not received callback on the subsequent activity: the task has not been requested, has not timed out, and no error callback has been received. [06/17 09:29:40:559][ 0x282a7d8c0] Requested TaskIdentifier 120 2025-06-17 09:29:40.623337 +0530 nsurlsessiond SUBMITTING: com.apple.CFNetwork-cc-166-373-Task .&lt;120&gt;:A71666 default 2025-06-17 09:29:40.631280 +0530 dasd Submitted Activity: com.apple.CFNetwork-cc-166-373-Task .&lt;120&gt;:A71666 at priority 10 default Seen couple of rejection with for CPUUsagePolicy and MemoryPressurePolicy 2025-06-17 09:29:40.989360 +0530 dasd com.apple.CFNetwork-cc-166-373-Task .&lt;120&gt;:A71666:[ {name: CPUUsagePolicy, policyWeight: 5.000, response: {Decision: Must Not Proceed, Score: 0.00, Rationale: [{[Max allowed CPU Usage level]: Required:90.00, Observed:95.00},]}} {name: MemoryPressurePolicy, policyWeight: 5.000, response: {Decision: Must Not Proceed, Score: 0.00, Rationale: [{[memoryPressure]: Required:1.00, Observed:2.00},]}} ], FinalDecision: Must Not Proceed} default 2025-06-17 10:55:22.500277 +0530 dasd com.apple.CFNetwork-cc-166-373-Task .&lt;120&gt;:A71666:[ {name: MemoryPressurePolicy, policyWeight: 5.000, response: {Decision: Must Not Proceed, Score: 0.00, Rationale: [{[memoryPressure]: Required:1.00, Observed:2.00},]}} ], FinalDecision: Must Not Proceed} default And more an hour later then it throws with an error BUT NEVER indicated the same to client 2025-06-17 10:55:27.426549 +0530 WAVE PTX Task .&lt;120&gt; is for &lt;&gt;.&lt;&gt;.&lt;120&gt; default 2025-06-17 10:55:27.776951 +0530 nsurlsessiond Task .&lt;120&gt; summary for task failure {transaction_duration_ms=5147145, response_status=-1, connection=0, reused=1, request_start_ms=0, request_duration_ms=0, response_start_ms=0, response_duration_ms=0, request_bytes=0, response_bytes=0, cache_hit=false} default 2025-06-17 10:55:27.777096 +0530 nsurlsessiond NDSession &lt;714296D7-20F9-4A0A-8C31-71FB67F39A56&gt; Task .&lt;120&gt; for client will be retried after error Error Domain=_nsurlsessiondErrorDomain Code=6 UserInfo={NSErrorFailingURLStringKey=, NSErrorFailingURLKey=, _NSURLErrorRelatedURLSessionTaskErrorKey=, _NSURLErrorFailingURLSessionTaskErrorKey=} - code: 6 default Then It got resumed and says successful but never got any callback on the same to client 2025-06-17 10:55:28.877245 +0530 nsurlsessiond NDSession &lt;714296D7-20F9-4A0A-8C31-71FB67F39A56&gt; Task .&lt;120&gt; resuming default 2025-06-17 10:55:55.225456 +0530 nsurlsessiond Task .&lt;120&gt; received response, status 401 content K default 2025-06-17 10:55:55.250371 +0530 nsurlsessiond Task .&lt;120&gt; finished successfully default Please refer feedback for diagnose logs: https://feedbackassistant.apple.com/feedback/18173303

Hi everyone, I'm currently experimenting with building a simple DNS filter using Apple's Packet Tunnel framework. Here's the flow I'm trying to implement: Create a TUN interface Set up a UDP socket Read packets via packetFlow.readPackets Parse the raw IP packet Forward the UDP payload through the socket Receive the response from the server Reconstruct the IP packet with the response Write it back to the TUN interface using packetFlow.writePackets Here’s an example of an intercepted IP packet (DNS request): 45 00 00 3c 15 c4 00 00 40 11 93 d1 c0 a8 00 64 08 08 08 08 ed 6e 00 35 00 28 e5 c9 7f da 01 00 00 01 00 00 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 And here’s the IP packet I tried writing back into the TUN interface (DNS response): 45 00 00 89 5e 37 40 00 40 11 0b 11 08 08 08 08 c0 a8 00 64 00 35 ed 6e 00 75 91 e8 7f da 81 80 00 01 00 04 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 c0 0c 00 05 00 01 00 00 0c fb 00 11 04 74 69 6d 65 01 67 07 61 61 70 6c 69 6d 67 c0 17 c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 fd c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 7d c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 54 fb Unfortunately, it seems the packet is not being written back correctly to the TUN interface. I'm not seeing any expected DNS response behavior on the device. Also, I noticed that after creating the TUN, the interface address shows up as 0.0.0.0:0 in Xcode. The system log includes this message when connecting the VPN: NWPath does not have valid interface: satisfied (Path is satisfied), interface: utun20[endc_sub6], ipv4, dns, expensive, uses cellular Does anyone know how to properly initialize the TUN so that the system recognizes it with a valid IP configuration? Or why my written-back packet might be getting ignored? Any help would be appreciated!

IMPORTANT The resume rate limiter is now covered by the official documentation. See Use background sessions efficiently within Downloading files in the background. So, the following is here purely for historical perspective. NSURLSession’s background session support on iOS includes a resume rate limiter. This limiter exists to prevent apps from abusing the background session support in order to run continuously in the background. It works as follows: nsurlsessiond (the daemon that does all the background session work) maintains a delay value for your app. It doubles that delay every time it resumes (or relaunches) your app. It resets that delay to 0 when the user brings your app to the front. It also resets the delay to 0 if the delay period elapses without it having resumed your app. When your app creates a new task while it is in the background, the task does not start until that delay has expired. To understand the impact of this, consider what happens when you download 10 resources. If you pass them to the background session all at once, you see something like this: Your app creates tasks 1 through 10 in the background session. nsurlsessiond starts working on the first few tasks. As tasks complete, nsurlsessiond starts working on subsequent ones. Eventually all the tasks complete and nsurlsessiond resumes your app. Now consider what happens if you only schedule one task at a time: Your app creates task 1. nsurlsessiond starts working on it. When it completes, nsurlsessiond resumes your app. Your app creates task 2. nsurlsessiond delays the start of task 2 a little bit. nsurlsessiond starts working on task 2. When it completes, nsurlsessiond resumes your app. Your app creates task 3. nsurlsessiond delays the start of task 3 by double the previous amount. nsurlsessiond starts working on task 3. When it completes, nsurlsessiond resumes your app. Steps 8 through 11 repeat, and each time the delay doubles. Eventually the delay gets so large that it looks like your app has stopped making progress. If you have a lot of tasks to run then you can mitigate this problem by starting tasks in batches. That is, rather than start just one task in step 1, you would start 100. This only helps up to a point. If you have thousands of tasks to run, you will eventually start seeing serious delays. In that case it’s much better to change your design to use fewer, larger transfers. Note All of the above applies to iOS 8 and later. Things worked differently in iOS 7. There’s a post on DevForums that explains the older approach. Finally, keep in mind that there may be other reasons for your task not starting. Specifically, if the task is flagged as discretionary (because you set the discretionary flag when creating the task’s session or because the task was started while your app was in the background), the task may be delayed for other reasons (low power, lack of Wi-Fi, and so on). Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" (r. 22323366)

Question: What is the standard, most reliable way to manage temporary files associated with a URLSessionDownloadTask that has been terminated abnormally due to a network error or other issues? Details Hello, I'm currently developing a feature to download multiple files concurrently on iOS using URLSessionDownloadTask, and I have a question regarding the lifecycle of the temporary files created during this process. As I understand it, URLSessionDownloadTask stores incoming data in a temporary file within the tmp directory, typically with a name like CFNetworkDownload_*.tmp. In my testing, temporary files are managed correctly in the normal scenario. For instance, when I call the cancel() method on an active downloadTask and then release all references to it, the corresponding temporary file is automatically cleaned up from the tmp directory shortly after. However, the problem occurs when a download is interrupted abnormally due to external factors, such as a lost network connection. In this situation, the urlSession(_:task:didCompleteWithError:) delegate method is called, but the associated temporary file is not deleted and remains in the tmp directory. I've observed a particularly interesting behavior related to this. Immediately after the error occurs, if I check my app's storage usage in the iOS Settings app, the data size appears to have decreased momentarily. However, the tmp file has not actually been deleted, and after a short while, the storage usage is recalculated to include the size of this orphaned temporary file. Since my app does not support resuming interrupted downloads, these leftover files become orphaned and unnecessarily consume storage. Therefore, I want to ensure they are all reliably deleted. With this context, I'd like to ask the community: What is the standard, most reliable way to manage temporary files associated with a URLSessionDownloadTask that has been terminated abnormally due to a network error or other issues? I am wondering if there is an official guide or a framework-level API to handle these orphaned files. I would appreciate any advice from those with experience in this area. Thank you.

We have a Java application built for macOS. On the first launch, the application prompts the user to allow local network access. We've correctly added the NSLocalNetworkUsageDescription key to the Info.plist, and the provided description appears in the system prompt. After the user grants permission, the application can successfully connect to a local server using its hostname. However, the issue arises after the system is rebooted. When the application is launched again, macOS does not prompt for local network access a second time—which is expected, as the permission was already granted. Despite this, the application is unable to connect to the local server. It appears the previously granted permission is being ignored after a reboot. A temporary workaround is to manually toggle the Local Network permission off and back on via System Settings > Privacy & Security, which restores connectivity—until the next reboot. This behavior is highly disruptive, both for us and for a significant number of our users. We can reproduce this on multiple systems... The issues started from macOS Sequoia 15.0 By opening the application bundle using "Show Package Contents," we can launch the application via "JavaAppLauncher" without any issues. Once started, the application is able to connect to our server over the local network. This seems to bypass the granted permissions? "JavaAppLauncher" is also been used in our Info.plist file

We have a Java application built for macOS. On the first launch, the application prompts the user to allow local network access. We've correctly added the NSLocalNetworkUsageDescription key to the Info.plist, and the provided description appears in the system prompt. After the user grants permission, the application can successfully connect to a local server using its hostname. However, the issue arises after the system is rebooted. When the application is launched again, macOS does not prompt for local network access a second time—which is expected, as the permission was already granted. Despite this, the application is unable to connect to the local server. It appears the previously granted permission is being ignored after a reboot. A temporary workaround is to manually toggle the Local Network permission off and back on via System Settings > Privacy & Security, which restores connectivity—until the next reboot. This behavior is highly disruptive, both for us and for a significant number of our users. We can reproduce this on multiple systems... The issues started from macOS Sequoia 15.0 By opening the application bundle using "Show Package Contents," we can launch the application via "JavaAppLauncher" without any issues. Once started, the application is able to connect to our server over the local network. This seems to bypass the granted permissions? "JavaAppLauncher" is also been used in our Info.plist file Removing the following plist in Recovery Mode seems to resolve the issue rm "/Volumes/Macintosh HD/Library/Preferences/com.apple.networkextension.plist" Is this safe to do?

We have a Java application built for macOS. On the first launch, the application prompts the user to allow local network access. We've correctly added the NSLocalNetworkUsageDescription key to the Info.plist, and the provided description appears in the system prompt. After the user grants permission, the application can successfully connect to a local server using its hostname. However, the issue arises after the system is rebooted. When the application is launched again, macOS does not prompt for local network access a second time—which is expected, as the permission was already granted. Despite this, the application is unable to connect to the local server. It appears the previously granted permission is being ignored after a reboot. A temporary workaround is to manually toggle the Local Network permission off and back on via System Settings > Privacy & Security, which restores connectivity—until the next reboot. This behavior is highly disruptive, both for us and for a significant number of our users. We can reproduce this on multiple systems... The issues started from macOS Sequoia 15.0 By opening the application bundle using "Show Package Contents," we can launch the application via "JavaAppLauncher" without any issues. Once started, the application is able to connect to our server over the local network. This seems to bypass the granted permissions? "JavaAppLauncher" is also been used in our Info.plist file Removing the following plist in Recovery Mode seems to resolve the issue rm "/Volumes/Macintosh HD/Library/Preferences/com.apple.networkextension.plist" Is this safe to do?

[Q] How many instances of the same NEFilterDataProvider subclass can there be in a single running Network Extension at any given time? I would expect that there can be only 1 instance but I'm looking at a memgraph where 2 instances are listed. As it's the Network Extension framework that is responsible for creating, starting and stopping these instances, this is rather strange.

At WWDC 25, Dr. Swetank mentioned, “DeviceDiscoveryUI is for making connections between apps and from an app to another device. It supports pairing with both Apple and third-party devices.” I find the pairing process in DeviceDiscoveryUI via Wi-Fi Aware intriguing. I have two questions: Can we pair devices via Bluetooth first and then establish a Wi-Fi Aware connection? If I use DeviceDiscoveryUI, how should I write an Android program to correspond with it and achieve iPhone-Android pairing? The app is an official Apple app: https://developer.apple.com/documentation/wifiaware/building-peer-to-peer-apps.

I was having a look through the documentation for NEPacketTunnelProvider, and wanted to know if it's possible for startTunnel(..) and stopTunnel(..) to run simultaneously, and thus require synchronization between resources they deal with? For example, if the VPN is toggled rapidly from system settings, could the setup that occurs in my startTunnel() definition (class instantiation and setTunnelNetworkSettings(value)) potentially occur after the tear-down logic (resource cleanup, setTunnelNetworkSettings(nil)), leaving the system in a state where the VPN is deactivated, but the configuration is in place?