Crash Analytics skill

Crash Analytics

You help triage, prioritize, and reduce app crashes — and understand how crash rate affects App Store discoverability and ratings.

Why Crash Rate Is an ASO Signal

• App Store ranking — Apple's algorithm penalizes apps with high crash rates
• App Store featuring — High crash rate disqualifies editorial consideration
• Ratings — Crashes are the #1 cause of 1-star reviews
• Retention — A crash in the first session destroys Day 1 retention

Target: crash-free sessions > 99.5% | crash-free users > 99%

Tools

Tool	What it provides	Setup
Firebase Crashlytics	Real-time crashes, ANRs, symbolicated stack traces	Add FirebaseCrashlytics pod/SPM package
App Store Connect	Crash rate trend, crashes per session	Built-in, no code needed
Xcode Organizer	Aggregated crash logs from TestFlight + App Store	Xcode → Window → Organizer → Crashes
MetricKit	On-device diagnostics, hang rate, launch time	iOS 13+, automatic

Recommended: Crashlytics (real-time alerts + search) + App Store Connect (trend validation)

Crashlytics Setup

iOS (Swift)

// AppDelegate or @main App struct
import FirebaseCore
import FirebaseCrashlytics

@main
struct MyApp: App {
    init() {
        FirebaseApp.configure()
        // Crashlytics is auto-initialized
    }
}

Non-fatal errors (track without crashing)

// Log a non-fatal error
Crashlytics.crashlytics().record(error: error)

// Log a custom key for debugging context
Crashlytics.crashlytics().setCustomValue(userId, forKey: "user_id")
Crashlytics.crashlytics().setCustomValue(screenName, forKey: "current_screen")

Android (Kotlin)

// build.gradle (app)
implementation("com.google.firebase:firebase-crashlytics:18.x.x")

// No additional code needed — auto-captures unhandled exceptions
// For non-fatal:
FirebaseCrashlytics.getInstance().recordException(throwable)

Triage Framework

Not all crashes are equal. Prioritize by impact:

Priority Score = Crash Frequency × Affected Users × User Segment Weight

Priority	Criteria	Response time
P0 — Critical	Crashes on launch / checkout / core feature; >1% of sessions	Fix today
P1 — High	Crashes in common flows; >0.1% of sessions	Fix this release
P2 — Medium	Edge case crashes; <0.1% of sessions	Fix next release
P3 — Low	Rare, non-blocking crashes; <0.01% of sessions	Backlog

Crashlytics Dashboard Triage

1. Sort by "Impact" (unique users affected), not frequency
2. Group: onboarding, checkout, core feature, background, launch
3. Assign P0/P1 to the top 3–5 issues
4. Set a velocity alert in Crashlytics for any issue affecting >0.5% of users

Reading a Crash Report

Fatal Exception: com.example.NullPointerException
  at com.example.UserProfileVC.loadData:87
  at com.example.HomeVC.viewDidLoad:45

Keys:
  user_id: 12345
  current_screen: "home"
  app_version: "2.3.1"
  os_version: "iOS 17.3"

Steps to debug:

1. Open the file and line in Xcode (UserProfileVC.swift:87)
2. Check what can be nil at that point
3. Reproduce with the user context (OS version, device, screen)
4. Write a failing test before fixing

Symbolication

Crashlytics auto-symbolicates if you upload dSYMs. If you see unsymbolicated traces:

# Manually upload dSYMs
./Pods/FirebaseCrashlytics/upload-symbols -gsp GoogleService-Info.plist -p ios MyApp.app.dSYM

For Bitcode-enabled builds, download dSYMs from App Store Connect → Activity → Build → dSYMs.

App Store Connect Crash Data

• App Store Connect → App Analytics → Crashes — Crash rate trend per version
• Compare crash rate before and after each release
• A spike on a specific version = regression in that release

Crash rate formula: Crashes / Sessions × 100

Release Strategy to Minimize Blast Radius

Use phased releases to catch crashes before full rollout:

iOS: App Store Connect → Version → Phased Release (7-day rollout: 1% → 2% → 5% → 10% → 20% → 50% → 100%)

Android: Play Console → Production → Managed publishing → Rollout percentage

Rule: Monitor Crashlytics for 24 hours at each phase. If crash rate increases >0.2%, pause rollout.

Responding to Crash-Driven 1-Star Reviews

1. Identify the app version where crash-related 1-stars appeared
2. Fix the crash
3. Reply to each crash-related review: "Fixed in version X.X — please update"
4. After update ships, use rating-prompt-strategy to recover rating

Output Format

Crash Audit Report

Stability Report — [App Name] v[version] ([period])

Crash-free sessions: [X]%  (target: >99.5%)
Crash-free users:    [X]%  (target: >99%)
Top crash issues:

P0 Issues (fix immediately):
  #1 [Exception type] — [X] users, [X]% of sessions
     File: [filename:line]
     Cause: [hypothesis]
     Fix: [specific action]

P1 Issues (this release):
  #2 [Exception type] — [X] users, [X]% of sessions
     ...

Action Plan:
  Today:     Fix P0 issue #1 → release hotfix
  This week: Fix P1 issues #2, #3 → include in v[X.X]
  Monitoring: Set velocity alert at 0.5% session threshold

Related Skills

• app-analytics — Full analytics stack; Crashlytics is one piece
• rating-prompt-strategy — Recover rating after fixing crash-driven 1-stars
• review-management — Respond to crash-related reviews
• retention-optimization — Crashes on Day 1 destroy retention metrics
• app-store-featured — Crash rate > 2% disqualifies editorial featuring