Symbolicate the .NET runtime frames in an Android tombstone file. Extracts BuildIds and PC offsets from the native backtrace, downloads debug symbols from the Microsoft symbol server, and runs llvm-sy
Install
The skill file stays in the publisher's repository.
Paste the copied command in a terminal. It installs this SKILL.md into that agent.
npx skills add dotnet/skills --skill android-tombstone-symbolication -a cursor -y
Symbolicate the .NET runtime frames in an Android tombstone file. Extracts BuildIds and PC offsets from the native backtrace, downloads debug symbols from the Microsoft symbol server, and runs llvm-symbolizer to produce function names with source file and line numbers. USE FOR triaging a .NET MAUI or Mono Android app crash from a tombstone, resolving native backtrace frames in libmonosgen-2.0.so or libcoreclr.so to .NET runtime source code, or investigating SIGABRT, SIGSEGV, or other native signals originating from the .NET runtime on Android. DO NOT USE FOR pure Java/Kotlin crashes, managed .NET exceptions that are already captured in logcat, or iOS crash logs. INVOKES Symbolicate-Tombstone.ps1 script, llvm-symbolizer, Microsoft symbol server.
name: android-tombstone-symbolication
description: Symbolicate the .NET runtime frames in an Android tombstone file. Extracts BuildIds and PC offsets from the native backtrace, downloads debug symbols from the Microsoft symbol server, and runs llvm-symbolizer to produce function names with source file and line numbers. USE FOR triaging a .NET MAUI or Mono Android app crash from a tombstone, resolving native backtrace frames in libmonosgen-2.0.so or libcoreclr.so to .NET runtime source code, or investigating SIGABRT, SIGSEGV, or other native signals originating from the .NET runtime on Android. DO NOT USE FOR pure Java/Kotlin crashes, managed .NET exceptions that are already captured in logcat, or iOS crash logs. INVOKES Symbolicate-Tombstone.ps1 script, llvm-symbolizer, Microsoft symbol server.
license: MIT
Android Tombstone .NET Symbolication
Resolves native backtrace frames from .NET Android app crashes (MAUI, Xamarin, Mono) to function names, source files, and line numbers using ELF BuildIds and Microsoft's symbol server.
Inputs: Tombstone file or logcat crash output, llvm-symbolizer (from Android NDK or any LLVM 14+ toolchain), internet access for symbol downloads.
Do not use when: The crash is a managed .NET exception (visible in logcat with a managed stack trace), the crashing library is not a .NET component (e.g., libart.so), or the tombstone is from iOS.
Workflow
Step 1: Parse the Tombstone Backtrace
Each backtrace frame has this format:
#NN pc OFFSET /path/to/library.so (optional_symbol+0xNN) (BuildId: HEXSTRING)
Extract: frame number, PC offset (hex, already library-relative), library name, and BuildId (32–40 hex chars).
Symbolicate all threads by default (background threads like GC/finalizer often have useful .NET frames). The crashing thread's backtrace is listed first; additional threads appear after --- --- --- markers.
Format notes:
The script auto-detects #NN pc frame lines with or without a backtrace: header, and strips logcat timestamp/tag prefixes automatically.
Logcat-captured tombstones often omit BuildIds. Recover via adb shell readelf -n, CI build artifacts, or the .NET runtime NuGet package.
GitHub issue pastes may mangle #1 pc into issue links — replace org/repo#N pc with #N pc before saving to a file.
If the script fails to parse a format, fall back to manual extraction of #NN pc OFFSET library.so (BuildId: HEX) tuples.
NativeAOT: No libcoreclr.so or libmonosgen-2.0.so — the runtime is statically linked into the app binary (e.g., libMyApp.so). The libSystem.*.so BCL libraries remain separate and can be symbolicated via the symbol server. For the app binary itself, you need the app's own debug symbols.
Skip libc.so, libart.so, and other Android system libraries unless the user specifically asks.
Step 3: Download Debug Symbols
For each unique .NET BuildId, download debug symbols:
Verify with file libmonosgen-2.0.so.debug — should show ELF 64-bit ... with debug_info, not stripped. If the download returns 404 or HTML, symbols are not published for that build. Do not add or subtract library base addresses — offsets in tombstones are already library-relative.
Flags: -CrashingThreadOnly (limit to crashing thread), -OutputFile path (write to file), -ParseOnly (report libraries/BuildIds/URLs without downloading), -SkipVersionLookup (skip runtime version identification).
Finding llvm-symbolizer
Check the Android NDK first: $ANDROID_NDK_ROOT/toolchains/llvm/prebuilt/*/bin/llvm-symbolizer or $ANDROID_HOME/ndk/*/toolchains/llvm/prebuilt/*/bin/llvm-symbolizer. Also available via brew install llvm, apt install llvm, or xcrun --find llvm-symbolizer on macOS.
If unavailable, complete steps 1–3 and present the download commands and llvm-symbolizer commands for the user to run. Do not spend time installing LLVM.
The script identifies the exact .NET runtime version by matching BuildIds against locally-installed runtime packs. It searches: SDK packs ($DOTNET_ROOT/packs/), NuGet cache (~/.nuget/packages/), and NuGet.org as an online fallback. When found, it extracts the version and source commit from the .nuspec<repository commit="..." /> element. Pass -SkipVersionLookup to disable. Requires llvm-readelf (auto-discovered from the NDK).
Validation
file <debug-file> shows ELF ... with debug_info, not stripped
At least one .NET frame resolves to a function name (not ??)
No .NET frames found: Report parsed frames and stop.
All frames resolved: Present symbolicated backtrace. Do not trace into source or attempt to build/debug the runtime.
Symbols not available (404): One attempt per BuildId, then stop. Report unsymbolicated frames with BuildIds and offsets.
llvm-symbolizer not available: Use -ParseOnly, present manual commands. Do not install LLVM.
Common Pitfalls
Missing BuildIds: Logcat tombstones often omit BuildIds. Recover via: adb shell readelf -n /path/to/lib.so, CI build artifacts, or the runtime NuGet package (~/.dotnet/packs/Microsoft.NETCore.App.Runtime.Mono.android-arm64/<version>/). Prefer pulling raw tombstone files (adb shell cat /data/tombstones/tombstone_XX) which always include BuildIds.
Symbols not found (404): Pre-release/internal builds may not publish symbols. Check for local unstripped .so/.so.dbg in build artifacts or the NuGet runtime pack.
NativeAOT: No runtime .so in the tombstone — runtime is in the app binary. libSystem.*.so BCL libraries still work with the symbol server; the app binary needs its own debug symbols.
Wrong llvm-symbolizer version: Use LLVM 14+ for best DWARF compatibility.
Multiple BuildIds: Each .NET library has its own BuildId — download symbols for each separately.
How do I install android-tombstone-symbolication?
Download plugins/dotnet-diag/skills/android-tombstone-symbolication/SKILL.md from the publisher, or copy the path and open the repository. PlugMCP lists the skill and does not host the file.
Where does android-tombstone-symbolication live?
The publisher keeps it at https://github.com/dotnet/skills.
Which agents can use android-tombstone-symbolication?
Claude, Cursor, and Codex can read a SKILL.md you add from the publisher's repository.