[ONE Android Development] Timmmmaaahh!:
I've provided support for a user via PM and I've narrowed it down to WhatsApp indeed crashing due to a notification sound bug.

[MENTION=6859839]kishpatel[/MENTION] If it's still useful, here's the log:

03-13 08:19:00.049 E/JavaBinder(28708): !!! FAILED BINDER TRANSACTION !!! (parcel size = 8916)
03-13 08:19:00.050 W/ActivityThread(28708): Bundle stats:
03-13 08:19:00.050 W/ActivityThread(28708): android:viewHierarchyState [size=2036]
03-13 08:19:00.051 W/ActivityThread(28708): android:views [size=1932]
03-13 08:19:00.052 W/ActivityThread(28708): android:support:fragments [size=5928]
03-13 08:19:00.052 W/ActivityThread(28708): PersistableBundle stats:
03-13 08:19:00.052 W/ActivityThread(28708): [null]
03-13 08:19:00.053 D/AndroidRuntime(28708): Shutting down VM
03-13 08:19:00.053 E/AndroidRuntime(28708): FATAL EXCEPTION: main
03-13 08:19:00.053 E/AndroidRuntime(28708): Process: com.whatsapp, PID: 28708
03-13 08:19:00.053 E/AndroidRuntime(28708): DeadSystemException: The system died; earlier logs will point to the root cause
03-13 08:19:00.093 W/ActivityManager(22651): Force finishing activity com.whatsapp/.Conversation
03-13 08:19:00.100 I/ActivityManager(22651): Showing crash dialog for package com.whatsapp u0
03-13 08:19:00.100 W/BroadcastQueue(22651): Background execution not allowed: receiving Intent { act=android.intent.action.DROPBOX_ENTRY_ADDED flg=0x10 (has extras) } to com.google.android.gms/.stats.service.DropBoxEntryAddedReceiver
03-13 08:19:00.101 W/BroadcastQueue(22651): Background execution not allowed: receiving Intent { act=android.intent.action.DROPBOX_ENTRY_ADDED flg=0x10 (has extras) } to com.google.android.gms/.chimera.GmsIntentOperationService$PersistentTrustedReceiver
03-13 08:19:00.182 W/Adreno-EGL(22651): <qeglDrvAPI_eglGetConfigAttrib:607>: EGL_BAD_ATTRIBUTE
03-13 08:19:00.189 D/vndksupport(22651): Loading /vendor/lib/hw/gralloc.msm8974.so from current namespace instead of sphal namespace.
03-13 08:19:00.596 W/ActivityManager(22651): Activity pause timeout for ActivityRecord{801e60f u0 com.whatsapp/.Conversation t1301 f}
03-13 08:19:00.827 W/Notification(24616): Use of stream types is deprecated for operations other than volume control
03-13 08:19:00.827 W/Notification(24616): See the documentation of setSound() for what to use instead with android.media.AudioAttributes to qualify your playback use case
03-13 08:19:00.828 E/JavaBinder(24616): !!! FAILED BINDER TRANSACTION !!! (parcel size = 8128)
03-13 08:19:02.394 I/ActivityManager(22651): Killing 28708:com.whatsapp/u0a108 (adj 0): crash
03-13 08:19:02.395 W/ActivityManager(22651): Scheduling restart of crashed service com.whatsapp/.messaging.MessageService in 1000ms
03-13 08:19:02.408 W/zygote (22651): kill(-28708, 9) failed: No such process
03-13 08:19:02.416 W/ActivityManager(22651): Scheduling restart of crashed service com.whatsapp/.appwidget.WidgetService in 11000ms
03-13 08:19:02.440 W/ActivityManager(22651): Force removing ActivityRecord{1a49631 u0 com.whatsapp/.HomeActivity t1301}: app died, no saved state
03-13 08:19:02.449 I/WindowManager(22651): Failed to capture screenshot of Token{3bd1116 ActivityRecord{1a49631 u0 com.whatsapp/.HomeActivity t1301 f}} appWin=Window{976da69 u0 com.whatsapp/com.whatsapp.HomeActivity} drawState=4
03-13 08:19:02.494 I/ActivityManager(22651): START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10300000 cmp=com.whatsapp/.Main (has extras)} from uid 10108
03-13 08:19:02.541 W/zygote (22651): kill(-28708, 9) failed: No such process
03-13 08:19:02.548 W/Adreno-EGL(24146): <qeglDrvAPI_eglGetConfigAttrib:607>: EGL_BAD_ATTRIBUTE
03-13 08:19:02.548 D/vndksupport(24146): Loading /vendor/lib/hw/gralloc.msm8974.so from current namespace instead of sphal namespace.
03-13 08:19:02.564 E/ActivityManager(22651): applyOptionsLocked: Unknown animationType=0
03-13 08:19:02.585 I/ActivityManager(22651): Start proc 769:com.whatsapp/u0a108 for activity com.whatsapp/.Main
03-13 08:19:02.586 W/zygote (22651): kill(-28708, 9) failed: No such process
03-13 08:19:02.591 I/qti_sensors_hal(22651): LIS3DH Accelerometer: batch 50.00 0.00
03-13 08:19:02.602 W/Looper (22651): Dispatch took 209ms on android.ui, h=Handler (com.android.server.am.AppErrorDialog$1) {4d49b89} cb=null msg=3
03-13 08:19:02.606 W/ActivityManager(22651): setHasOverlayUi called on unknown pid: 28708
03-13 08:19:02.629 W/zygote (22651): kill(-28708, 9) failed: No such process
03-13 08:19:02.630 I/zygote (22651): Successfully killed process cgroup uid 10108 pid 28708 in 221ms
03-13 08:19:02.663 W/zygote (769): ClassLoaderContext size mismatch. expected=1, actual=2 (PCL[] | PCL[];PCL[/data/dalvik-cache/xposed_XResourcesSuperClass.dex*2802528989:/data/dalvik-cache/xposed_XTypedArraySuperClass.dex*708326108])
03-13 08:19:02.673 W/AppOps (22651): Finishing op nesting under-run: uid 1000 pkg android code 24 time=0 duration=0 nesting=0
03-13 08:19:02.859 I/MultiDex(769): VM with version 2.1.0 has multidex support
03-13 08:19:02.859 I/MultiDex(769): Installing application
03-13 08:19:02.859 I/MultiDex(769): VM has multidex support, MultiDex support library is disabled.
03-13 08:19:02.863 D/Event (769): No subscribers registered for event class com.whatsapp.j.i
03-13 08:19:02.863 D/Event (769): No subscribers registered for event class b.a.a.g
03-13 08:19:02.864 W/Notification(24616): Use of stream types is deprecated for operations other than volume control
03-13 08:19:02.865 W/Notification(24616): See the documentation of setSound() for what to use instead with android.media.AudioAttributes to qualify your playback use case
03-13 08:19:02.868 E/JavaBinder(24616): !!! FAILED BINDER TRANSACTION !!! (parcel size = 8128)
03-13 08:19:02.882 I/WhatsApp(769): LL_I D [1647:Wam_post]:199378 wartuntime/send/mh-disconnected
03-13 08:19:02.883 I/WhatsApp(769): LL_I D [1646:Wam_internal]:199127 wambuffer/initfromfile: opened existing wam file: record_count = 61, event_count = 7, attribute_count = 18, size = 337, create_ts = 1520908800, rotated_size = 0
03-13 08:19:02.915 I/WhatsApp(769): LL_I D [2:main]:236065 message_handler/logged_flag/must_reconnect initialize to true
03-13 08:19:02.915 I/WhatsApp(769): LL_I D [2:main]:236065 message_handler/logged_flag/must_ignore_network_once initialize to false
03-13 08:19:02.916 I/WhatsApp(769): LL_I D [2:main]:236065 message_handler/logged_flag/disconnected initialize to true
03-13 08:19:02.950 D/ActivityThread(769): Loading provider com.whatsapp.provider.contact: com.whatsapp.contact.ContactProvider
03-13 08:19:02.957 I/WhatsApp(769): LL_I D [2:main]:295434 messagethumbcache/construct 24576
03-13 08:19:02.968 I/WhatsApp(769): LL_I D [1657:pool-2-thread-1]:244030 ProcessMediaQueue/attemptDequeueRequest no requests available
03-13 08:19:02.971 I/WhatsApp(769): LL_I D [1658:pool-2-thread-2]:244030 ProcessMediaQueue/attemptDequeueRequest no requests available
03-13 08:19:02.971 I/WhatsApp(769): LL_I D [1661:pool-3-thread-1]:244030 ProcessMediaQueue/attemptDequeueRequest no requests available
03-13 08:19:02.972 I/WhatsApp(769): LL_I D [1659:pool-2-thread-3]:244030 ProcessMediaQueue/attemptDequeueRequest no requests available
03-13 08:19:02.972 I/WhatsApp(769): LL_I D [1660:pool-2-thread-4]:244030 ProcessMediaQueue/attemptDequeueRequest no requests available
03-13 08:19:02.978 I/WhatsApp(769): LL_I D [2:main]:248577 PAY: PaymentsManager isPaymentCountry enabled for country: XXX currency: XXX (scrubbed)
03-13 08:19:02.979 I/WhatsApp(769): LL_I D [2:main]:248606 PAY: PaymentsManager:isPaymentsEnabled: true for country code: XX with server props: false is enabled locally: false
03-13 08:19:02.981 I/WhatsApp(769): LL_I D [2:main]:172686 ContactsSyncAdapter/created
03-13 08:19:02.990 D/FirebaseApp(769): com.google.firebase.auth.FirebaseAuth is not linked. Skipping initialization.
03-13 08:19:02.994 D/FirebaseApp(769): com.google.firebase.crash.FirebaseCrash is not linked. Skipping initialization.
03-13 08:19:02.996 I/WhatsApp(769): LL_I D [1664:WhatsApp Worker #1]:213076 gdrive-conditions-manager/can-use-network/active_network/cellular
03-13 08:19:02.997 I/WhatsApp(769): LL_I D [1664:WhatsApp Worker #1]:213042 gdrive-conditions-manager/can-use-network/message-restore/true
03-13 08:19:02.997 I/WhatsApp(769): LL_I D [1664:WhatsApp Worker #1]:213043 gdrive-conditions-manager/can-use-network/media-restore/false
03-13 08:19:02.998 I/WhatsApp(769): LL_I D [1664:WhatsApp Worker #1]:213044 gdrive-conditions-manager/can-use-network/backup/false
03-13 08:19:03.001 I/FA (769): App measurement is starting up, version: 11020
03-13 08:19:03.001 I/FA (769): To enable debug logging run: adb shell setprop log.tag.FA VERBOSE
03-13 08:19:03.013 I/FA (769): To enable faster debug mode event logging run:
03-13 08:19:03.013 I/FA (769): adb shell setprop debug.firebase.analytics.app com.whatsapp
03-13 08:19:03.019 I/FirebaseInitProvider(769): FirebaseApp initialization successful
03-13 08:19:03.026 E/JavaBinder(769): !!! FAILED BINDER TRANSACTION !!! (parcel size = 9220)
03-13 08:19:03.027 D/AndroidRuntime(769): Shutting down VM
03-13 08:19:03.027 E/AndroidRuntime(769): FATAL EXCEPTION: main
03-13 08:19:03.027 E/AndroidRuntime(769): Process: com.whatsapp, PID: 769
03-13 08:19:03.027 E/AndroidRuntime(769): DeadSystemException: The system died; earlier logs will point to the root cause
03-13 08:19:03.031 E/WhatsApp(769): LL_E D [2:main]:107772 UNCAUGHT EXCEPTION; exception=java.lang.RuntimeException: android.os.DeadSystemException
03-13 08:19:03.031 E/WhatsApp(769): ### begin stack trace 2.18.65-play-release
03-13 08:19:03.031 E/WhatsApp(769): java.lang.RuntimeException: android.os.DeadSystemException
03-13 08:19:03.031 E/WhatsApp(769):	at android.app.ActivityThread.installContentProviders(ActivityThread.java:5843)
03-13 08:19:03.031 E/WhatsApp(769):	at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5748)
03-13 08:19:03.031 E/WhatsApp(769):	at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
03-13 08:19:03.031 E/WhatsApp(769):	at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:361)
03-13 08:19:03.031 E/WhatsApp(769):	at android.app.ActivityThread.handleBindApplication(<Xposed>)
03-13 08:19:03.031 E/WhatsApp(769):	at android.app.ActivityThread.-wrap1(Unknown Source:0)
03-13 08:19:03.031 E/WhatsApp(769):	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1672)
03-13 08:19:03.031 E/WhatsApp(769):	at android.os.Handler.dispatchMessage(Handler.java:106)
03-13 08:19:03.031 E/WhatsApp(769):	at android.os.Looper.loop(Looper.java:164)
03-13 08:19:03.031 E/WhatsApp(769):	at android.app.ActivityThread.main(ActivityThread.java:6520)
03-13 08:19:03.031 E/WhatsApp(769):	at java.lang.reflect.Method.invoke(Native Method)
03-13 08:19:03.031 E/WhatsApp(769):	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:442)
03-13 08:19:03.031 E/WhatsApp(769):	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
03-13 08:19:03.031 E/WhatsApp(769):	at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:108)
03-13 08:19:03.031 E/WhatsApp(769): Caused by: android.os.DeadSystemException
03-13 08:19:03.031 E/WhatsApp(769):	... 14 more
03-13 08:19:03.031 E/WhatsApp(769): ### end stack trace
03-13 08:19:03.032 E/WhatsApp(769): LL_E D [2:main]:107815 Unable to create crash sentinel file; exception=java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.io.File.createNewFile()' on a null object reference
03-13 08:19:03.032 E/WhatsApp(769): ### begin stack trace 2.18.65-play-release
03-13 08:19:03.032 E/WhatsApp(769): java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.io.File.createNewFile()' on a null object reference
03-13 08:19:03.032 E/WhatsApp(769):	at com.whatsapp.App$1.uncaughtException(:107773)
03-13 08:19:03.032 E/WhatsApp(769):	at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1068)
03-13 08:19:03.032 E/WhatsApp(769):	at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1063)
03-13 08:19:03.032 E/WhatsApp(769):	at java.lang.Thread.dispatchUncaughtException(Thread.java:1955)
03-13 08:19:03.032 E/WhatsApp(769): ### end stack trace
03-13 08:19:03.033 V/WhatsApp(769): LL_V D [2:main]:291555 log/flush/start
03-13 08:19:03.033 V/WhatsApp(769): LL_V D [2:main]:291567 log/flush/logs written
03-13 08:19:03.033 V/WhatsApp(769): LL_V D [2:main]:291568 log/flush/forcing to disk
03-13 08:19:03.034 V/WhatsApp(769): LL_V D [2:main]:291576 log/flush/end
03-13 08:19:03.036 W/ActivityManager(22651): Force finishing activity com.whatsapp/.Main

ROM Settings Backup can do this for you but I do wonder why you're so paranoid about Google's backup system. After all you're using their services anyway so if privacy is any concern it's already bust from the moment you accepted their license terms. Besides all that, setting a notification tone is a problematic effort to you? I don't want to judge or anything but that's kinda silly... :silly: