NEPacketTunnelFlow crash in dispatch queue

Attached is the full crash report …

I don’t see that. Please post a reply with the full crash report attached there. See Posting a Crash Report for more details.

here is a snippet

That suggests your process has crashed due to an unhandled language exception. In most cases such crash reports will include a Last Exception Background Backtrace section that’s key to determining what’s gone wrong.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Weird. I could have sworn I attached it. Try #2. I also don't see anything that indicates a "Last Exception Background"

Try #2.

Got it. Thanks.

I also don't see anything that indicates a "Last Exception Back…"

Yep. This is an annoying limitation of our crash reporting infrastructure. The Last Exception Backtrace section is only present for Objective-C exceptions. The crash reporter is unable to provide for this C++ exceptions )-: See this post, and its follow-ups, for the full backstory.

So, the only thing you have to go on is the crashing thread’s backtrace:

Thread 13 Crashed::  Dispatch queue: NEPacketTunnelFlow queue
0   libsystem_kernel.dylib  … __pthread_kill + 10
1   libsystem_pthread.dylib … pthread_kill + 263
2   libsystem_c.dylib       … abort + 123
3   libc++abi.dylib         … abort_message + 241
4   libc++abi.dylib         … demangling_terminate_handler() + 241
5   libobjc.A.dylib         … _objc_terminate() + 104
6   libc++abi.dylib         … std::__terminate(void (*)()) + 6
7   libc++abi.dylib         … std::terminate() + 54
8   libdispatch.dylib       … _dispatch_client_callout + 28
9   libdispatch.dylib       … _dispatch_continuation_pop + 463
10  libdispatch.dylib       … _dispatch_source_invoke + 2184
11  libdispatch.dylib       … _dispatch_lane_serial_drain + 393
12  libdispatch.dylib       … _dispatch_lane_invoke + 366
13  libdispatch.dylib       … _dispatch_workloop_worker_thread + 765
14  libsystem_pthread.dylib … _pthread_wqthread + 327
15  libsystem_pthread.dylib … start_wqthread + 15

Frames 15 through 8 are standard Dispatch stuff, namely, a Dispatch worker thread servicing a queue. Frames 7 through 0 are the C++ exception handler terminating the process because the C++ exception went unhandled. So far, so generic.

About the only useful thing is the thread name, NEPacketTunnelFlow queue. This suggests that the unhandled exception is coming from the C++ code that you run to handle the flow. I recommend that you add a catch-all exception handler to that code to ensure that it can’t throw C++ exception out to the system. So, where you have code like this:

[flow readPacketObjectsWithCompletionHandler:^(NSArray<NEPacket *> * _Nonnull packets) {
    … call C++ …
}];

make sure that you handle any C++ exceptions coming up from below.

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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Quinn,

Thanks that helps a lot.