Unknown crash in Fabric [FIRAAlarm cancel]

Question

After I released a new version of my app using XCode8, this crash was reported in Fabric:

#0. Crashed: com.apple.main-thread
0  libdispatch.dylib              0x187c89834 dispatch_source_cancel + 4
1  Appname                    0x1003d866c -[FIRAAlarm cancel] + 4298868332
2  Appname                    0x1003d8318 -[FIRAAlarm runAfterDelay:withBlock:] + 4298867480
3  Appname                    0x1003fc054 -[FIRASessionReporter rescheduleSessionStartTimer] + 4299014228
4  CoreFoundation                 0x188d9622c __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20
5  CoreFoundation                 0x188d95930 _CFXRegistrationPost + 400
6  CoreFoundation                 0x188d956ac ___CFXNotificationPost_block_invoke + 60
7  CoreFoundation                 0x188e04b9c -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1504
8  CoreFoundation                 0x188cd7bf4 _CFXNotificationPost + 376
9  Foundation                     0x1897de6bc -[NSNotificationCenter postNotificationName:object:userInfo:] + 68
10 UIKit                          0x18ecca284 <redacted> + 1212
11 UIKit                          0x18eecdd20 <redacted> + 2744
12 UIKit                          0x18eee2080 <redacted> + 48
13 UIKit                          0x18eeca8c4 <redacted> + 168
14 FrontBoardServices             0x18a99d8bc <redacted> + 36
15 FrontBoardServices             0x18a99d728 <redacted> + 176
16 FrontBoardServices             0x18a99dad0 <redacted> + 56
17 CoreFoundation                 0x188daa278 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
18 CoreFoundation                 0x188da9bc0 __CFRunLoopDoSources0 + 524
19 CoreFoundation                 0x188da77c0 __CFRunLoopRun + 804
20 CoreFoundation                 0x188cd6048 CFRunLoopRunSpecific + 444
21 UIKit                          0x18ecb05dc <redacted> + 608
22 UIKit                          0x18ecab360 UIApplicationMain + 208
23 Appname                    0x1000f6724 main (main.m:15)
24 libdispatch.dylib              0x187cb85b8 (Missing)

The crash detail doesn't show any specific file, just this information:

Appname
#CrashNumber-[FIRAAlarm cancel]

Any ideas what this “FIRAAlarm” is?

Answer 1

This is a known Firebase issue and will be fixed in their next release: https://groups.google.com/forum/#!topic/firebase-talk/W-gPv4tmXpw