I'm facing trouble to find out the cause of crash that happens in ios11.1 of my app.I have tried to look out and explore but can't find the reason or nor reproduce it yet.Following is the stack trace provided by Fabric (Crashlytics).#3. Crashed: com.apple.CFNetwork.Connection0 libsystem_kernel.dylib 0x184ca1348 __pthread_kill + 81 libsystem_pthread.dylib 0x184db5344 pthread_kill$VARIANT$mp + 3962 libsystem_c.dylib 0x184c10fb8 abort + 1403 libsystem_c.dylib 0x184be4a9c basename_r + 3144 CFNetwork 0x18589d460 invocation function for block in TCPIOConnection::_tlsProcessValidateServerCertificates(nw_tls_context*) + 6705 CFNetwork 0x18589b884 TCPIOConnection::_handleTLSEvent(nw_tls_context*, tls_handshake_message_t, void () block_pointer, bool) + 7006 libnetwork.dylib 0x186076964 __tcp_connection_set_tls_message_handler_on_nw_connection_block_invoke + 1687 libboringssl.dylib 0x185f4eb4c __boringssl_context_handshake_message_handler_block_invoke + 1608 libdispatch.dylib 0x184b0d088 _dispatch_call_block_and_release + 249 libdispatch.dylib 0x184b0d048 _dispatch_client_callout + 1610 libdispatch.dylib 0x184b16e48 _dispatch_queue_serial_drain$VARIANT$mp + 52811 libdispatch.dylib 0x184b177d8 _dispatch_queue_invoke$VARIANT$mp + 34012 libdispatch.dylib 0x184b16d00 _dispatch_queue_serial_drain$VARIANT$mp + 20013 libdispatch.dylib 0x184b177d8 _dispatch_queue_invoke$VARIANT$mp + 34014 libdispatch.dylib 0x184b18200 _dispatch_root_queue_drain_deferred_wlh$VARIANT$mp + 40015 libdispatch.dylib 0x184b204a0 _dispatch_workloop_worker_thread$VARIANT$mp + 64416 libsystem_pthread.dylib 0x184db2fd0 _pthread_wqthread + 93217 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4--#0. com.apple.main-thread0 libsystem_kernel.dylib 0x184c80bc4 mach_msg_trap + 81 libsystem_kernel.dylib 0x184c80a3c mach_msg + 722 CoreFoundation 0x185131c74 __CFRunLoopServiceMachPort + 1963 CoreFoundation 0x18512f840 __CFRunLoopRun + 14244 CoreFoundation 0x18504ffb8 CFRunLoopRunSpecific + 4365 GraphicsServices 0x186ee7f84 GSEventRunModal + 1006 UIKit 0x18e6242f4 UIApplicationMain + 208...8 libdyld.dylib 0x184b7256c start + 4#1. Thread0 libsystem_kernel.dylib 0x184ca1dbc __workq_kernreturn + 81 libsystem_pthread.dylib 0x184db3134 _pthread_wqthread + 12882 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#2. Thread0 libsystem_kernel.dylib 0x184ca1dbc __workq_kernreturn + 81 libsystem_pthread.dylib 0x184db2fa0 _pthread_wqthread + 8842 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#3. Crashed: com.apple.CFNetwork.Connection0 libsystem_kernel.dylib 0x184ca1348 __pthread_kill + 81 libsystem_pthread.dylib 0x184db5344 pthread_kill$VARIANT$mp + 3962 libsystem_c.dylib 0x184c10fb8 abort + 1403 libsystem_c.dylib 0x184be4a9c basename_r + 3144 CFNetwork 0x18589d460 invocation function for block in TCPIOConnection::_tlsProcessValidateServerCertificates(nw_tls_context*) + 6705 CFNetwork 0x18589b884 TCPIOConnection::_handleTLSEvent(nw_tls_context*, tls_handshake_message_t, void () block_pointer, bool) + 7006 libnetwork.dylib 0x186076964 __tcp_connection_set_tls_message_handler_on_nw_connection_block_invoke + 1687 libboringssl.dylib 0x185f4eb4c __boringssl_context_handshake_message_handler_block_invoke + 1608 libdispatch.dylib 0x184b0d088 _dispatch_call_block_and_release + 249 libdispatch.dylib 0x184b0d048 _dispatch_client_callout + 1610 libdispatch.dylib 0x184b16e48 _dispatch_queue_serial_drain$VARIANT$mp + 52811 libdispatch.dylib 0x184b177d8 _dispatch_queue_invoke$VARIANT$mp + 34012 libdispatch.dylib 0x184b16d00 _dispatch_queue_serial_drain$VARIANT$mp + 20013 libdispatch.dylib 0x184b177d8 _dispatch_queue_invoke$VARIANT$mp + 34014 libdispatch.dylib 0x184b18200 _dispatch_root_queue_drain_deferred_wlh$VARIANT$mp + 40015 libdispatch.dylib 0x184b204a0 _dispatch_workloop_worker_thread$VARIANT$mp + 64416 libsystem_pthread.dylib 0x184db2fd0 _pthread_wqthread + 93217 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#4. Thread0 libsystem_kernel.dylib 0x184ca1dbc __workq_kernreturn + 81 libsystem_pthread.dylib 0x184db2fa0 _pthread_wqthread + 8842 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#5. com.apple.NSURLSession-work0 libsystem_kernel.dylib 0x184ca01a4 __bsdthread_ctl + 81 libsystem_pthread.dylib 0x184dbefb8 _pthread_set_properties_self + 642 libdispatch.dylib 0x184b13818 _dispatch_set_priority_and_mach_voucher_slow$VARIANT$mp + 1603 libdispatch.dylib 0x184b139c8 _dispatch_set_priority_and_voucher_slow$VARIANT$mp + 2324 libdispatch.dylib 0x184b16f50 _dispatch_queue_serial_drain$VARIANT$mp + 7925 libdispatch.dylib 0x184b177d8 _dispatch_queue_invoke$VARIANT$mp + 3406 libdispatch.dylib 0x184b18200 _dispatch_root_queue_drain_deferred_wlh$VARIANT$mp + 4007 libdispatch.dylib 0x184b204a0 _dispatch_workloop_worker_thread$VARIANT$mp + 6448 libsystem_pthread.dylib 0x184db2fd0 _pthread_wqthread + 9329 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#6. com.apple.uikit.eventfetch-thread0 libsystem_kernel.dylib 0x184c80bc4 mach_msg_trap + 81 libsystem_kernel.dylib 0x184c80a3c mach_msg + 722 CoreFoundation 0x185131c74 __CFRunLoopServiceMachPort + 1963 CoreFoundation 0x18512f840 __CFRunLoopRun + 14244 CoreFoundation 0x18504ffb8 CFRunLoopRunSpecific + 4365 Foundation 0x185a796e4 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 3046 Foundation 0x185a98afc -[NSRunLoop(NSRunLoop) runUntilDate:] + 967 UIKit 0x18f1832f4 -[UIEventFetcher threadMain] + 1368 Foundation 0x185b7a860 __NSThread__start__ + 9969 libsystem_pthread.dylib 0x184db431c _pthread_body + 30810 libsystem_pthread.dylib 0x184db41e8 _pthread_body + 31011 libsystem_pthread.dylib 0x184db2c28 thread_start + 4#7. com.apple.root.default-qos0 libsystem_kernel.dylib 0x184ca1648 __semwait_signal + 81 libsystem_c.dylib 0x184bbaf70 nanosleep + 2122 libsystem_c.dylib 0x184c23f30 sleep + 443 Disco 0x100c957c8 mosquitto_loop_forever (mosquitto.c:1059)4 Disco 0x100d15654 partial apply for Analytics.(connect() -> Bool).(closure #1) (Disco.swift:1259)5 libdispatch.dylib 0x184b0d088 _dispatch_call_block_and_release + 246 libdispatch.dylib 0x184b0d048 _dispatch_client_callout + 167 libdispatch.dylib 0x184b14090 _dispatch_queue_override_invoke$VARIANT$mp + 7168 libdispatch.dylib 0x184b1a1c8 _dispatch_root_queue_drain + 5969 libdispatch.dylib 0x184b19f10 _dispatch_worker_thread3 + 12010 libsystem_pthread.dylib 0x184db3120 _pthread_wqthread + 126811 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#8. com.twitter.crashlytics.ios.MachExceptionServer0 libsystem_kernel.dylib 0x184c80bc4 mach_msg_trap + 81 libsystem_kernel.dylib 0x184c80a3c mach_msg + 722 MyAPP... 0x10074a7a8 CLSMachExceptionServer + 43177184403 libsystem_pthread.dylib 0x184db431c _pthread_body + 3084 libsystem_pthread.dylib 0x184db41e8 _pthread_body + 3105 libsystem_pthread.dylib 0x184db2c28 thread_start + 4#9. Thread0 libsystem_kernel.dylib 0x184ca1dbc __workq_kernreturn + 81 libsystem_pthread.dylib 0x184db2fa0 _pthread_wqthread + 8842 libsystem_pthread.dylib 0x184db2c20 start_wqthread + 4#10. com.apple.NSURLConnectionLoader0 libsystem_kernel.dylib 0x184c80bc4 mach_msg_trap + 81 libsystem_kernel.dylib 0x184c80a3c mach_msg + 722 CoreFoundation 0x185131c74 __CFRunLoopServiceMachPort + 1963 CoreFoundation 0x18512f840 __CFRunLoopRun + 14244 CoreFoundation 0x18504ffb8 CFRunLoopRunSpecific + 4365 CFNetwork 0x1857ba264 +[NSURLConnection(Loader) _resourceLoadLoop:] + 4046 Foundation 0x185b7a860 __NSThread__start__ + 9967 libsystem_pthread.dylib 0x184db431c _pthread_body + 3088 libsystem_pthread.dylib 0x184db41e8 _pthread_body + 3109 libsystem_pthread.dylib 0x184db2c28 thread_start + 4