Hi, I would like to know if it is safe to call the uploadTask from URLSession from the main thread ? We've a user who is reporting repeated crashes at startup, here is the stack we see: Exception Type: EXC_CRASH (SIGKILL) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: FRONTBOARD 2343432205 <RBSTerminateContext| domain:10 code:0x8BADF00D explanation:scene-update watchdog transgression: app<com.appspot.myApp(E7590BB1-722C-491D-9199-F867DE4B880A)>:2212 exhausted real (wall clock) time allowance of 10.00 seconds ProcessVisibility: Background ProcessState: Running WatchdogEvent: scene-update WatchdogVisibility: Background WatchdogCPUStatistics: ( "Elapsed total CPU time (seconds): 21.260 (user 10.230, system 11.030), 35% CPU", "Elapsed application CPU time (seconds): 0.006, 0% CPU" ) reportType:CrashLog maxTerminationResistance:Interactive> Triggered by Thread: 0 Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 libsystem_kernel.dylib 0x1def7a688 mach_msg2_trap + 8 1 libsystem_kernel.dylib 0x1def7dd98 mach_msg2_internal + 80 2 libsystem_kernel.dylib 0x1def7dcb0 mach_msg_overwrite + 424 3 libsystem_kernel.dylib 0x1def7dafc mach_msg + 24 4 libdispatch.dylib 0x1968d8f14 _dispatch_mach_send_and_wait_for_reply + 544 5 libdispatch.dylib 0x1968d92b4 dispatch_mach_send_with_result_and_wait_for_reply + 60 6 libxpc.dylib 0x21714a930 xpc_connection_send_message_with_reply_sync + 256 7 Foundation 0x18d80a3ac __NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY__ + 16 8 Foundation 0x18d806b14 -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] + 2160 9 CoreFoundation 0x18eb868dc ___forwarding___ + 1004 10 CoreFoundation 0x18eb86430 _CF_forwarding_prep_0 + 96 11 CFNetwork 0x1900c71e0 -[__NSURLBackgroundSession setupBackgroundSession] + 800 12 CFNetwork 0x1900b3e80 -[__NSURLBackgroundSession initWithConfiguration:delegate:delegateQueue:delegateDispatchQueue:] + 552 13 CFNetwork 0x1900b4784 +[NSURLSession _sessionWithConfiguration:delegate:delegateQueue:delegateDispatchQueue:] + 1496 14 MyApp 0x1054210b4 CombineBgXferRepository.session.getter (in MyApp) (CombineBgXferRepository.swift:62) + 7966900 15 MyApp 0x105422fa4 CombineBgXferRepository.startUploadTask(fileURL:request:) (in MyApp) (CombineBgXferRepository.swift:310) + 7974820 If it is ok to call this uploadTask from the main thread, does this crash indicate a problem with the operating system? Are there scenarios where the background upload service does not respond to requests?