Guide to accessing device logs on iOS and Android for Capacitor apps. Covers command-line tools, GUI applications, filtering, and real-time streaming. Use this skill when users need to view device logs for debugging.

iOS and Android Logs for Capacitor Apps Pick the log channel that actually carries the message you need, filter to the app, capture to a file, hand off to diagnosis. When to Use TRIGGER when: User asks how to view, stream, filter, or save device/simulator logs. console.log output or ⚡️ Capacitor lines are missing on iOS/Android. User needs a crash report ( .ips , tombstone, ANR) from a device or simulator. Logcat or the unified log is too noisy; user wants only their app or plugin. A log command fails or misbehaves: level error still shows everything, unable to find utility "devicectl" , Error: Unexpected argument 'log' , adb: no devices/emulators found . Do not use: Interpreting the error and fixing the app debugging capacitor . Production crash/ANR reporting (Sentry, Crashlytics, Datadog) capacitor native observability . AI agent log streaming via MCP servers capacitor mcp . CPU/memory profiling capacitor performance . UIScene lifecycle migration capacitor uiscene migration . Where Capacitor Output Goes (the main trap) Source iOS Android Capacitor bridge messages ( ⚡️ Loading app at ... , ⚡️ To Native , errors) stdout only ( print ) logcat tag Capacitor and Capacitor/<Sub JS console.log/warn/error mirrored natively stdout as ⚡️ [log] ... logcat tag Capacitor/Console as File: ... Line N Msg: ... JS console, full fidelity (objects, stack traces) Safari Web Inspector chrome://inspect Plugin/app code using os.Logger / NSLog unified log (Console.app, log stream ) n/a Plugin code using android.util.Log / Capacitor Logger n/a logcat Native crash .ips crash report FATAL EXCEPTION in logcat + crash buffer; tombstone for native code Consequences: On iOS, Console.app and log stream will not show Capacitor's ⚡️ lines or mirrored JS console. Use Xcode's console, xcrun simctl launch console pty , or xcrun devicectl device process launch console . Mirroring obeys loggingBehavior ( none debug production , default debug ): Release builds produce no Capacitor logs unless set to production . The iOS process name is the executable ( App in the Capacitor template), not the display name. Filter with process == "App" . Quick Commands Procedure 1. Identify target : Simulator/emulator vs physical device; Debug vs Release; which layer emitted the message (table above). 2. Check connectivity : xcrun simctl list devices booted , xcrun devicectl list devices (device must be unlocked, trusted, Developer Mode on), adb devices l . 3. Clear and reproduce : adb logcat c on Android; on iOS start the stream before relaunching the app. 4. Filter early by process/PID, then by subsystem/tag, then by text. Never paste unfiltered system logs into a conversation. 5. Save to a file ( app.log , .logarchive , adb bugreport ) when the user needs to share it; redact tokens, emails, and auth headers before sharing outside the team. 6. Hand off the relevant lines to debugging capacitor for root cause work. Error Handling Message Fix level error still shows every message log stream level only understands default , info , debug (it sets the floor, not a ceiling). Filter errors with predicate 'messageType == error OR messageType == fault' . xcrun: error: unable to find utility "devicectl" Active dev dir is Command Line Tools. sudo xcode select s /Applications/Xcode.app/Contents/Developer . Error: Unexpected argument 'log' (devicectl) devicectl has no log streaming subcommand. Use console for stdout, Console.app or log collect device udid for unified logs. log collect fails with a permission error Run with sudo ; device must be unlocked and trusted. No devices are booted. (simctl) xcrun simctl boot "<device name " or open Simulator. adb: no devices/emulators found / unauthorized Enable USB debugging, accept the RSA prompt, adb kill server && adb start server . adb logcat pid= prints everything / errors App not running so pidof returned nothing. Launch the app first. No Capacitor/Console lines on Android loggingBehavior: 'none' , or Release build with default debug . JS logs show but objects print as [object Object] Native mirroring stringifies; use the WebView inspector for structured output. Verification iOS sim: launch with console pty , see ⚡️ Loading app at capacitor://localhost and a test console.log('log check') as ⚡️ [log] log check . iOS device: same via devicectl device process launch console . Android: adb logcat s Capacitor/Console:V shows Msg: log check . Unified log: a plugin Logger(subsystem: "com.example.app", category: "test").info("log check") appears with predicate 'subsystem == "com.example.app"' level info . References Only load a reference when its topic is in play. File Load when references/ios logs.md Unified log predicates, Console.app, log collect / log show , iOS crash reports via devicectl/Xcode, adding os.Logger to a plugin references/android logs.md logcat buffers/formats/filters, Android Studio Logcat queries, ANRs, tombstones, bugreports, WebView ( chromium ) noise Resources https://developer.apple.com/documentation/os/logging https://developer.apple.com/documentation/xcode/acquiring crash reports and diagnostic logs https://developer.android.com/tools/logcat https://developer.android.com/studio/debug/logcat https://capacitorjs.com/docs/config

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