How to interpret crash reports that are not fully symbolicated in firebase?

Question

We use firebase crash analytics in our app, it helped us solve bugs quick by specifying function name and even line numbers too, but sometimes it only gives

appDelegate.swift [start + 17644]

how can I intrpret this report? and why it appears like that ?

this is the full trace with threads, the app name is replaced by appName

Exception name: EXC_SOFTWARE / UNCAUGHT_NS_EXCEPTION
1 CoreFoundation __exceptionPreprocess + 1241536
2 libobjc.A.dylib objc_exception_throw + 34136
3 CoreFoundation -[__NSPlaceholderDictionary initWithObjects:forKeys:count:] + 80952
4 CoreFoundation +[NSDictionary dictionaryWithObjects:forKeys:count:] + 80552
5 FBSDKCoreKit 4304632780 + 244684
6 FBSDKCoreKit 4304632048 + 243952
7 FBSDKCoreKit 4304437716 + 49620
8 CoreFoundation __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 823848
9 CoreFoundation _CFXRegistrationPost + 821548
10 CoreFoundation ___CFXNotificationPost_block_invoke + 820904
11 CoreFoundation -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1276824
12 CoreFoundation _CFXNotificationPost + 44016
13 Foundation -[NSNotificationCenter postNotificationName:object:userInfo:] + 26152
14 UIKit -[UIApplication _deactivateForReason:notify:] + 491392
15 CoreFoundation __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 823848
16 CoreFoundation ___CFXRegistrationPost_block_invoke + 823692
17 CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 905564
18 CoreFoundation __CFRunLoopDoBlocks + 903512
19 CoreFoundation __CFRunLoopRun + 896080
20 CoreFoundation CFRunLoopRunSpecific + 36932
21 GraphicsServices GSEventRunModal + 49556
22 UIKit -[UIApplication _run] + 504568
23 UIKit UIApplicationMain + 483376
24 appName main (AppDelegate.swift:18)
25 libdyld.dylib start + 17844

Thread 2
1 libsystem_kernel.dylib mach_msg_trap + 4460
2 libsystem_kernel.dylib mach_msg + 4056
3 CoreFoundation __CFRunLoopServiceMachPort + 904424
4 CoreFoundation __CFRunLoopRun + 895236
5 CoreFoundation CFRunLoopRunSpecific + 36932
6 Foundation -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 51848
7 Foundation -[NSRunLoop(NSRunLoop) runUntilDate:] + 185720
8 UIKit -[UIEventFetcher threadMain] + 10422824
9 Foundation __NSThread__start__ + 1090680
10 libsystem_pthread.dylib _pthread_body + 14412
11 libsystem_pthread.dylib _pthread_start + 14172
12 libsystem_pthread.dylib thread_start + 3496

Thread 3
1 libsystem_kernel.dylib mach_msg_trap + 4460
2 libsystem_kernel.dylib mach_msg + 4056
3 CoreFoundation __CFRunLoopServiceMachPort + 904424
4 CoreFoundation __CFRunLoopRun + 895236
5 CoreFoundation CFRunLoopRunSpecific + 36932
6 CFNetwork +[NSURLConnection(Loader) _resourceLoadLoop:] + 847820
7 Foundation __NSThread__start__ + 1090680
8 libsystem_pthread.dylib _pthread_body + 14412
9 libsystem_pthread.dylib _pthread_start + 14172
10 libsystem_pthread.dylib thread_start + 3496

Thread 4
1 libsystem_kernel.dylib mach_msg_trap + 4460
2 libsystem_kernel.dylib mach_msg + 4056
3 CoreFoundation __CFRunLoopServiceMachPort + 904424
4 CoreFoundation __CFRunLoopRun + 895236
5 CoreFoundation CFRunLoopRunSpecific + 36932
6 Foundation -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 51848
7 Foundation -[NSRunLoop(NSRunLoop) run] + 397836
8 appName +[GAI threadMain:] + 1782640
9 Foundation __NSThread__start__ + 1090680
10 libsystem_pthread.dylib _pthread_body + 14412
11 libsystem_pthread.dylib _pthread_start + 14172
12 libsystem_pthread.dylib thread_start + 3496

Thread 5
1 libsystem_kernel.dylib mach_msg_trap + 4460
2 libsystem_kernel.dylib mach_msg + 4056
3 appName google_breakpad::ExceptionHandler::WaitForMessage(void*) + 2388144
4 libsystem_pthread.dylib _pthread_body + 14412
5 libsystem_pthread.dylib _pthread_start + 14172
6 libsystem_pthread.dylib thread_start + 3496

Thread 6
1 libsystem_kernel.dylib mach_msg_trap + 4460
2 libsystem_kernel.dylib mach_msg + 4056
3 CoreFoundation __CFRunLoopServiceMachPort + 904424
4 CoreFoundation __CFRunLoopRun + 895236
5 CoreFoundation CFRunLoopRunSpecific + 36932
6 GeoServices _runNetworkThread + 4308864
7 libsystem_pthread.dylib _pthread_body + 14412
8 libsystem_pthread.dylib _pthread_start + 14172
9 libsystem_pthread.dylib thread_start + 3496

Thread 7
1 libsystem_kernel.dylib __workq_kernreturn + 129672
2 libsystem_pthread.dylib _pthread_wqthread + 4952 
3 libsystem_pthread.dylib start_wqthread + 3488 arrow_drop_down

Thread 8
1 libsystem_kernel.dylib __workq_kernreturn + 129672
2 libsystem_pthread.dylib _pthread_wqthread + 4468 
3 libsystem_pthread.dylib start_wqthread + 3488 arrow_drop_down

Thread 9
1 libsystem_kernel.dylib __workq_kernreturn + 129672
2 libsystem_pthread.dylib _pthread_wqthread + 4952
3 libsystem_pthread.dylib start_wqthread + 3488

Thread 10
1 CoreFoundation> -[__NSDictionaryM countByEnumeratingWithState:objects:count:] + 86492
2 appName +[FIRAEvent normalizedParametersForParameters:isPublicEvent:] + 1999144 3 appName +[FIRAEvent normalizedParametersForParameters:isPublicEvent:] + 1999144 4 appName -[FIRAEvent initWithOrigin:isPublic:name:timestamp:previousTimestamp:parameters:] + 2002028
5 appName +[FIRAnalytics logEventOnSerialQueueWithOrigin:isPublicEvent:name:parameters:timestamp:ignoreEnabled:ignoreInterceptor:addedScreenParameters:] + 2195924
6 appName __65+[FIRAnalytics logEventWithOrigin:isPublicEvent:name:parameters:]_block_invoke_3 + 2195040
7 libdispatch.dylib _dispatch_call_block_and_release + 4604
8 libdispatch.dylib _dispatch_client_callout + 4540
9 libdispatch.dylib _dispatch_queue_serial_drain + 62528
10 libdispatch.dylib _dispatch_queue_invoke + 18852
11 libdispatch.dylib _dispatch_root_queue_drain + 70536
12 libdispatch.dylib _dispatch_worker_thread3 + 69864
13 libsystem_pthread.dylib _pthread_wqthread + 4788
14 libsystem_pthread.dylib start_wqthread + 3488

Answer 1

Your app crashed because of an exception. As your data doesn't show the exception string, it is unknown what kind of exception triggered the crash.

The exception was raised due to a problem in the FBSDKCoreKit framework, which is likely the Facebook 3rd party SDK. As you most likely didn't upload the debug symbols of that framework to Firebase, they couldn't symbolicate them and provide the classes and methods being called in those frames.

The exception is triggered by a problem with handling of an NSDictionary object, could be trying to insert a nil value for a key, but that is just a guess.

As the only non system frames in the resulting stack trace are from your apps call, Firebase grouped the crashes by that call instead of the calls in FBSDKCoreKit.

To learn more about those crashes you need to upload the symbols of the FBSDKCoreKit framework. With the given information it is impossible to know what the crash is about and how to fix it.