FirebaseAppCheck crashes on watchdog in background

[KeepCalmAndPush]

My iOS app began crashing not long ago, probably after transitioning to iOS 17.4, Xcode 15.3.
Crash happens several times a day when app is in background. Crashlogs say there is some sudden work on main thread, lasting over 10 seconds:

ProcessVisibility: Background
ProcessState: Running
WatchdogEvent: scene-update
WatchdogVisibility: Background
WatchdogCPUStatistics: (
"Elapsed total CPU time (seconds): 11.330 (user 10.970, system 0.360), 18% CPU",
"Elapsed application CPU time (seconds): 10.682, 17% 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        	       0x1e008649c __psynch_cvwait + 8
1   libsystem_pthread.dylib       	       0x1f3b0c590 _pthread_cond_wait + 1228
2   Foundation                    	       0x1970c9310 -[NSOperation waitUntilFinished] + 508
3   CoreFoundation                	       0x197b50648 _CFXNotificationPost + 792
4   Foundation                    	       0x1969e2f10 -[NSNotificationCenter postNotificationName:object:userInfo:] + 92
5   FirebaseAppCheck              	       0x103de137c -[FIRAppCheck postTokenUpdateNotificationWithToken:] + 212
6   FirebaseAppCheck              	       0x103de1294 -[FIRAppCheck tokenDidUpdate:serviceName:] + 80
7   AppCheckCore                  	       0x1037aa8e8 __27-[GACAppCheck refreshToken]_block_invoke.18 + 248
8   FBLPromises                   	       0x103d45130 __56-[FBLPromise chainOnQueue:chainedFulfill:chainedReject:]_block_invoke.18 + 52
9   libdispatch.dylib             	       0x19fa1d13c _dispatch_call_block_and_release + 32
10  libdispatch.dylib             	       0x19fa1edd4 _dispatch_client_callout + 20
11  libdispatch.dylib             	       0x19fa2d5ec _dispatch_main_queue_drain + 1060
12  libdispatch.dylib             	       0x19fa2d1b8 _dispatch_main_queue_callback_4CF + 44
13  CoreFoundation                	       0x197b5951c __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 16
14  CoreFoundation                	       0x197b56218 __CFRunLoopRun + 1996
15  CoreFoundation                	       0x197b55968 CFRunLoopRunSpecific + 608
16  GraphicsServices              	       0x1dbe534e0 GSEventRunModal + 164
17  UIKitCore                     	       0x199fc8edc -[UIApplication _run] + 888
18  UIKitCore                     	       0x199fc8518 UIApplicationMain + 340
19  MY_APP                         	       0x102cd69bc 0x102868000 + 4647356
20  dyld                          	       0x1bb076d84 start + 2240

The version of Firebase* pods I use is 10.22. Maybe this is a known bug fixed in later versions?

[morganchen12]

Moving this to an issue (#12547). Thanks for reporting @KeepCalmAndPush